The publication of new material other than the Watch Tower magazine (for which the Editorial Committee was arranged), and especially the publication of the Golden Age periodical, was a clear violation of the Will. Note the wording of the sentence:
"As the Society has already pledged to me that it will publish no other periodicals, it shall also be required that the Editorial Committee shall write for or be connected with no other publications in any manner or degree" (Watch Tower, 1 December 1916, p. 358).
This is a blanket statement. And the record shows that the Society abided by these wishes in 1917, at least in appearance. The only material distributed this year were old publications (such as Studies in the Scriptures, Manna and other already-published books and booklets, Proto-Drama of Creation Scenarios) and the Watch Tower magazine (cf. 15 December 1917 Watch Tower, pp. 374-375). The one exception was the Finished Mystery book, but it was styled as a posthumous work of Russell that had already been written and published according to his wishes:
"Time and again Pastor Russell said that the Seventh Volume of STUDIES IN THE SCRIPTURES would be written; and it was expected that he would write it. The Scriptures show that the Seventh Volume must be published. Pastor Russell passed from the earth, and the Seventh Volume remained unpublished.... But the fact is, he did write it. This book may properly be said to be a posthumous publication of Pastor Russell. Why? Because to him the Lord gave the “key”, to him was given the privilege of making clear to the Church in its last years the “Mystery of God”; to him was granted the privilege of hearing from the hands of the Lord to the Household of Faith “meat in due season” for the special development and sustenance of God’s dear little ones. This service he has faithfully performed. ... With the “key” which Brother Russell, as the Lord’s servant, had placed in his hands, Brother Woodworth, by the Lord’s grace, has been enabled to bring together everything that Brother Russell wrote on Revelation" (The Finished Mystery, 1917, pp. 5-6).
In reality, Russell had very little to do with the writing of the Finished Mystery, but this cover story accommodated the publication of the book to the stated wishes in the Will. Many Bible Students were not sold on this story and expressed doubts that it really was written by Russell. A letter by Frank F. Cook to Mr. Charles R. Cox, written in August-September 1917, for instance states: "I have no thought that Brother Russell would ever have permitted such a message going out to the people....It is important to bear in mind that there has been a tradition among us that the 7th Volume had to be written, and after Brother Russell's death, not being able to find any manuscripts among the things that he left behind, somebody had to get busy and get out the volume that the friends might not be disappointed and one of our cherished expectations might not lack fulfillment". The book was also published without the knowledge or authorization of the Board of Directors, and it was copyrighted in the name of the People's Pulpit Association rather than the Watch Tower Bible and Tract Society (the "Society" mentioned in the Will).
Moreover, Rutherford was already violating the Will in other ways by imposing new bylaws that made him a President for life and dismissing the four directors that did not support him, so any "fidelity" to the Will was in appearance only. The printing of internal pamphlets in 1917 and 1918 in the wake of the Paul SL Johnson/Board of Directors schisms constituted another possible breach of the Will; although they were not intended for public circulation, they were published for Bible Students and printed with donated funds. In his response Harvest Siftings Reviewed, Paul SL Johnson noted two other little-noticed breaches of the Will with repect to publications: "He [Rutherford] suggested the publication of one, and admittedly permitted the publication of two of his discourses as volunteer matter. The Will directs that volunteer matter consist of Bro. Russell’s discourses. He should have refrained from such a suggestion. He should also have prevented others overriding the Will in this matter" (pp. 19-20). Johnson's opinion of Rutherford's treatment of the Will is as follows:
"Let us stand for Bro. Russell’s wise arrangements! Let us stand for Bro. Russell’s Will! Let us stand for Bro. Russell’s Board! Let us stand for Bro. Russell’s charter! Let us stand for Bro. Russell’s W. T. B. & T. S.! The Society’s only right to the things that Bro. Russell bequeathed to it is that the intents of his writings, will, and charter be obeyed. No one has a right to exercise any authority in the Society, unless he submits to Bro. Russell’s expressed wishes respecting those bequests. These Bro. Rutherford has disregarded; and therefore has morally forfeited the right to exercise any authority with respect to the W. T. B. & T. S. Will not the shareholders bring such pressure to bear by their votes as to enforce compliance with them, and set aside those who do not comply with them? Would not Bro. Walter Page, a former vice-president, make a much better President than Bro. Rutherford?" (Paul SL Johnson, Harvest Siftings Reviewed, 1 November 1917, p. 18-19).
When Rutherford and the remaining directors were released from prison in 1919, Rutherford flagrantly disregarded the Will's wishes on publication by starting a new periodical, the Golden Age, intended for public distribution. As Timothy White notes, "Many Bible Students were too shocked at this unfaithfulness [to the Will] to engage in The Golden Age distribution" (p. 186). Rutherford directly addressed this problem in the 15 October 1919 Watch Tower (p. 318):
Here Rutherford insists that he is still abiding to the Will but interprets it extremely liberally. His idiosyncratic reading is that the Will forbids only the establishment of a journal that rivals the Watch Tower. Since the Golden Age was intended to be an auxiliary to the Watch Tower, subordinate to it, Rutherford claims that he is being faithful to the Will. Of course, the Will actually says nothing about forbidding a publication rivalling the Watch Tower; it states in no uncertain terms that the Society "will publish no other periodicals" and "will be connected with no other publications in any manner or degree". Furthermore, the statement that the Society will "publish no other periodicals" is interpolated with Rutherford's interpretive comment that this means that the Society "will not enter into a general publishing business, but will confine its activities to the publication of the truth". Again, such a reading has no basis in the actual Will itself.
In 1933, Rutherford later expressed his disdain towards the Will and its demands on publication in the following way: "The dreamers, who are opposers, wept and howled, and still weep and howl, because the 'last will and testament of a dead man was not strictly followed,' assuming that any man could put a restriction on God's work" (Preparation, 1933, p. 117).
Hope this helps!