Very rare I think. But given the internal bitter schism within the Air Force regarding B-52s in Vietnam, and especially the polarizing events of Linebacker II and its regrettable tactics, it is not surprising that some careers were trashed.
I am not familiar with your great uncle. But my guess is he was one of the "good guys" who balked at the absurd B-52 tactics that caused loss of lives, and who paid a price for being both outspoken and right.
Whether there was actually a "mutiny" at Anderson AFB in Guam is debatable. But there obviously was a major confrontation between the B-52 crews and the Generals. This incident and the failures of Linebacker II were mostly covered up for a few years, until a former B-52 pilot (Drenkowski) published a 1977 article in the Armed Forces Journal, "The Tragedy of Linebacker II." This was later expanded in Soldier of Fortune magazine, where he alleges the refusal of crews to fly ('mutiny') not only in Guam, but also in U-Tapao.
The Air force soon rebutted all the allegations in a follow-up Journal article.
There is no doubt there was animosity between the operators, and the SAC generals, most of whom planned the tactics in Omaha's Offutt AFB. They did not want to hear anything from the crews who had to fly ridiculous and dangerous flight patterns repeatedly, despite the losses.
Having flown in Linebacker II myself, watching the Buffs fly overhead and on radar, it was immediately evident to me that their tactics were wrong. And observing their burning losses in the night sky proved it!
A couple of weeks later a couple of Buff crews over a beer detailed an incredible standoff confrontation at the Anderson O'Club, where the crews refused to fly the next day unless the tactics were changed... and thankfully they were, finally but belatedly.
The 11 Days of Christmas
Operation Linebacker II - Triumph & Tragedy at 30,000 Feet
Bibliography