He didn’t lose the controls _or_ the instruments. He lost his HUD and the primary flight display. But the standby instrument display was still working correctly, and the fly–by–wire system was still accepting input and acting on it correctly. Sure, if those things had failed then ejecting would have been fine. But he didn’t even check them to see if they were still working or not, he just bailed out of a flyable plane.

I wonder how many planes they will lose if they trained the pilots to fly without HUD.

I'm willing to give him the benefit of the doubt. I've seen too many software systems that failed in undetectable ways, and the user was disbelieved. The damn thing is fly-by-wire and if the instruments are failing for unknown reasons, then I could easily believe that the controls started glitching too, and that this isn't reflected anywhere.

Interesting because I'm willing to give the US Marine Corp, which conducted a comprehensive investigation before firing him, the benefit of the doubt.

You're free to do that, but I'm not sure that this is the best thing in the world. Of the people who I know who were in the US military, generally the more highly placed they were, the less faith they had in the command structure.