That's exactly the question (I probably buried the lead!) DID THEY MAKE A BACKROOM DEAL to keep Freddy quiet about ripping the plenary power away from Knorr??
I don't think anybody outside the GB of the day really knows, but the Dunlap brothers had this theory: (and I agree with it) -
The formation of the GB was not really to rip power away from Knorr. It was to prevent Franz from ever gaining the ultimate power Knorr had. Knorr was never considered much of a religionist - that was Freddy. Knorr was a businessman who knew how to print stuff at low cost - even if he had to run Bethel like an 1840s slave plantation. He pretty much let the writers do what they wanted. Franz was off in Franz-land much of the time dreaming up his wild chronology. Everybody was afraid of what Franz might do if he were unchecked in power as president - he was considered even then to be somewhat senile, if not totally demented.
Ed Dunlap believed that a number of influential Bethelites knew there was something seriously wrong with all the chronology - yes, 607 - 1914 - 1975 - all of it - prior to 1975. They staged a little internal battle to de-emphasize the 1975 date. Freddy, of course, was dead set on his date: note that he even made up that nonsense about "we don't know how long Adam and Eve were in the garden before they sinned, but it could not have been long, or else they would have had kids" to extend the date just a little more after 1975. This is why so much of the speculation over 1975 was done by enthusiast talks at assemblies, but little was put in print.
The backroom deal (it is theorized) was that Freddy was made president after all - but as a paper tiger. Remember the Watchtower where they published the pictures of "the four presidents of the society"? Marion Dunlap thought this was a specific ploy to play to Freddies ego.
When Freddy realized that he could be outvoted, he started his outcry that the governing body was not scriptural and kept on whining about them as long as he lived.