SpaceX has 200 FS engineers, while DoD has 4k developers working on the F-35

I agree. Reading this I was thinking 'only 4k?'. I'd have thought flight management systems, radar and weapon systems to take at least that. And then you have all the other software... UI, ancillaries, engine control and monitoring, systems supervision, sensor data fusion, comms... Yeah 4k doesn't look much for this thing. Maybe they're thinking still working on it after delivery and even then, not that surprising.

Yeah, I was going to make a similar comment.

Also, why does the SpaceX comment in the tweet/article say "full stack"? I wonder if there's a bunch of embedded engineers at SpaceX that aren't being counted in this figure.