"If somebody cannot handle some crudeness, I’d postulate that he or she does not belong at a startup, regardless of gender. Because, when shit hits the fan, as it invariably does, we need people who can take it." What does crude language have to do with ability to handle startup situations where "shit hits the fan"? Someone who dislikes offensive language is somehow unable to handle fast-paced or stressful situations…
He's using it as a litmus test. When people are in fast-paced or stressful situations on the job, the mental "PC filter" can begin to break down, and people may say things they wouldn't have. You can condemn this, but it can happen to the best of us. When it does, it's nice to have a group of people whom the occasional uncouth or unthinking comment rolls off their back like water on ducks.
I can't think I've ever been so stressed out I started using racial or sexist slurs.