Toleration is what allows people who have different views to work together toward common goals. You can't have civilization without it, because no two people will agree on everything. If these people were really as boorish as the OP described, the best approach would have been to let them embarrass themselves.
What's next, hushing someone who dares admit he voted for a Republican? (I can imagine the rationale now: "you're enabling war and bigotry by proxy! Public GOPism is unacceptable!")
Allowing people to be sexist jerks (let's not dress it up as "boorish") doesn't just let them "embarrass" themselves, it creates an effect within a subculture that gives that activity preferential status because few people want to use their limited public credibility to counteract it--thereby over time letting sexist behavior become the expected norm of that subculture. That's not OK, and speaking up directly confronts the issue and prevents it from becoming a social norm, or becoming further entrenched because we live in a profoundly sexist society to begin with, in that subculture.