It may be that the sort of bravado that emerges in football-team-ish environments is useful to a startup. ... even if the things that made it enjoyable would be a net minus in isolation.
This part reads like veiled sexism to me. Sure, there are disclaimers and "I-don't-knows" and "might-be's" thrown about but in the absence of real data I don't think there are good reasons to bring this up other than to reinforce sexist stereotypes.
This is one of the problems of honest debate of politicized issues. Positing the obvious gets you labeled as a closet bigot.
Do you really consider it far fetched that there could exist a team that worked better when they were all the same gender? I'm not asking if you'd like such a team (I wouldn't), but it's fairly obvious to me with the variety of people that exist in the world that not only could such a team exist, but one almost certainly does. Have you not met a half-dozen socially awkward geeks (male or female) in your life that struggled with professional interaction with the opposite of sex?
An important mechanism of earnest debate is the ability to differentiate between ideals and observed reality. I, for instance, find dogmatic fundamentalism unsavory, but it obviously has the ability to wield both a cohesive social force and give rise to political power. It's intellectually dishonest to assume that things we don't like are unable to produce advantageous results.
This part reads like veiled sexism to me. Sure, there are disclaimers and "I-don't-knows" and "might-be's" thrown about but in the absence of real data I don't think there are good reasons to bring this up other than to reinforce sexist stereotypes.