That seems an acceptable interpretation only if it also means that "men and majorities could be incapable of joining the software profession based on their genetics."

Because both are encompassed by the more general "people could be incapable of joining the software profession based on their genetics."

And that's of course not the only interpretation possible, but the one you choose. You say it's because of "capability" but you could look at it in terms of "inclination", "interest", "comparative advantages" or other angles.

He literally had a list of suggestions for increasing the number of women in tech.

Much of the thrust of his essay was a critique of the methods being used to increase diversity, not of the goal or the feasibility of achieving the goal.

It was a technical critique. This method won’t work, kind of critique.

"Differences in traits" doesn't mean "incapable". You know what happens if you take a whole population and deprive them of adequate calcium and protein in their early years? You get a "difference in traits" as to their height. Damore made no Essentialist claims about race or gender. He was just trying to be helpful in explaining an observed phenomenon at one causal level back.

Mangalor said "should" rather than "could". Even then, I do not think that it could be interpreted like that. He talks about distributions of traits, the sentence that you quoted did not put minorities in a single box.