Mmm, but if you think about it, many successful WWII pilots (mostly Allied, I've noticed, but anyone with a basic knowledge of both sides can probably make an educated guess as to why) have dropped military aviation altogether and gone off in the opposite direction. Hell, a fair few guys barely talk about their war days, and for good reason.
I wouldn't see it as unlikely for him to do something similar to Admiral Bei once the Council of Elders and whoever have finished raiding him for knowledge. Although I do recall seeing somewhere that he meditated for a while with the Council, or something implying that he did. But after you've seen the horrors of war, and how futile the whole process is (how many people did the Alliance lose fighting the Shivans?), it'd be understandable for him to want to have nothing to do with the war at this point.
Or the cooler alternative, Fedayeen Operators knocking at his door and calling him out of retirement with the promise of flying.