This is an interesting TL, and by the way I do not see anything that occurred to him (other than death) preventing him from taking an active role in politics and going any which way. Moody man with trauma getting in politics? Done before. Aristo with no desire for power? I see you losing an Empire which defined your existence and raise you a traumatic experience of seeing utter nobodies claw their way to power as you stare on in disbelief. You might get interested in politics after that in a hurry to prevent the wrong folk from doing what you feel is bad. Being above politics? AH brothers, that's a cop-out. All those fine German fellas with monocles and ancient pedigrees that say they would have fought for Germany regardless of what sort of Germany it was and therefore were above politics... they would have been the first to organize death-squads had the Reds gotten a whiff of real power in Germany through the ballot box. They were above politics when a nationalist revanchist seized power. That's not staying above politics, that's declaring your politics.
And if all else fails, have him fall in with a crazed woman. Sure worked for Goering, whose anti-Semitism got a boost when he hooked up with sweet Swedish psycho Karin. Likewise Ludendorff went from kinda nuts to a squirrel preparing for winter once the Mrs. started directing traffic. It won't take much to push Richthofen into politics, at all.
Either way, someone should kick the tires on this. Though the research would be a pain, as you'd have to separate the Red Baron from Richthofen to figure out what sort of person he was, might have been and would have been.