One of the traits of "classical" AS (as it was understood before the last 5 years) was an resistence to conformity and uniformity. Mostly that resistence was in a passive form, like refusing to participate, intentionally acting/doing things differently in non-aggressive, non-disruptive ways or a natural distrust of peers or authority figures. So I would think that that alone who exclude AS people from wanting to join the military. However, AS people have joined the military, no doubt, but it seems a bad mix for a lot of them. My dad, who's very AS-like and probably does have AS, was in the Marines during the Korean War and HATED it. He never talks about it.
However, nowdays what passes for AS is so broad, who knows? For me, a natural, strong yet passive distrust of conformity and authority is indicative of AS, because it stems for our natural inclination to analyze, be cautious of what isn't readily transparent to us and be skeptical of anything that doesn't present a clear logic. I'm very much distrustful of anything conforming and authoritarian. I've always been passively resistent to pressures to conform, as far back as I remember. i never have jumped just because someone told me to, so to speak. So naturally, I would never, never seriously consider joining the military.