Just some random thoughts the subject and some comments brought to mind....
I have never had any confusion or questions about my own gender or 'manliness'.
But others sometimes do when considering me. I have a often quiet and thoughtful personality, and people sometimes make the mistake of thinking I have an alternate lifestyle. Growing up I learned to use/hide behind sports, craziness, being in the military, etc, to project a unambiguous man image. But it wasn't really me and over time I tired of pretending, and my sensitive nature battled for position. On a side note, this has always been very annoying, particularly when the person dislikes alternate lifestyle folks, which they are mistaking me for. It was already in my nature not to look down on people different from me, but it reinforced my empathy for those who actually are and face endless forms of harassment for it.
But sometimes I fall short of my man ideal, particularly the times I wussed-out in some situation (failed, in my mind). Sometimes I do OK, sometimes I fail. It's not predetermined for me. It always comes to a new choice each time.
I would think though, this is not a manhood issue only, because it is vitually the same for women. More of a bravery/cowardice struggle.
One of the reasons I believe I am aspie is my tendency to be very focused (or obsessive) in interests. And these vary, but include the off-mentioned interest in guns and blowing things up in general. But I do that to inanimate objects for fun & never to people or live creatures, because I do not like harming anything.
The exception was anything that might have been required of me, assuming it was a legal order, during my 27 years in Army & Air Force.
I have read somewhere, that Aspies actually are fairly well suited for the Military, as they respond well in a very ordered and consistant environment. For what it is worth, I would agree with that from my own experience. Becoming a civilian again when it was over, was quite difficult. But some above comments seem to express the opposite, so I guess it's not a cut & dry thing. I would say I too had difficulties, but it wasn't with the military/on duty aspect. It was the same old socializing problems off-duty, that could happen in any job, career, etc.