Eventually, the mistaken view regarding marriage that prompted the injustice was corrected, and Brother Diehl’s privileges of service were restored. His loyalty to Jehovah was rewarded.
Remember that the "mistaken view" regarding marriage was corrected not by spiritual guidance but just because N. H. Knorr decided that he wanted to get married.
The end result of this experience is just a reflection of how much the WT has changed over the years, under today's "divine" rulings the end could have been different. It comes to mind the couples that were DF back in the 70s for unnatural practices in their marriages and that they never got their sanctions rescinded or any sort of apologies.