"Women are less capable than men" is sexist; "The majority of women are physically and mentally incapable of running a Fortune 500 company" is a neutral hypothesis that can be asserted with anecdotal evidence, sociological studies, and if modern corporate leadership wasn't silent on the issue, there would also likely be firsthand testimony. <--- heresy
But on the other hand, you could likely present evidence to the contrary. The comparison of the opposing evidence, and the careful scrutiny of the facts that provide that evidence, is the most truthful approach to the question.
For the record, the commenter above who casually states that "most women can't run Fortune 500 companies because most men can't either" <---THAT is sexist
Please try not to misquote people you disagree with. The GP did not say most women can't because most men can't - they said most women can't and most men can't. I.e. most women can't because most people can't, which seems uncontroversial. It's a very hard job.
Unrelated: I don't understand what you mean by a "neutral" hypothesis. The hypothesis can be made for neutral or non-neutral goals, by a neutral or non-neutral person, but that's all true of any hypothesis.
> For the record, the commenter above who casually states that "most women can't run Fortune 500 companies because most men can't either" <---THAT is sexist
I think you read your biases into that, too:
> The statement “very few women are capable of running a Fortune 500 company effectively” is factually true, but implicitly sexist (very few men are capable either).
I read the "very few men are capable either" as "the problem is that running a F500 is hard, not being a women". There's also no "because" in there - they don't imply that women can't because men are mostly unable, they just say that it's similarly hard for men.
You're giving too little attention to social context. The latter statement will rarely be interpreted neutrally when uttered in societies where statements denigrating females' capabilities has been (or continues to be) a cultural norm.
For the record, the commenter above who casually states that "most women can't run Fortune 500 companies because most men can't either" <---THAT is sexist