what can you do, Sanji has always been a lover of women, imagine living on a island with only gay men that are lusting and chasing you for two whole years without a break. Talk about pent up sexual frustration.
While it is moronic it does provide comic relief and keeps with the original spirit of the Strawhat Pirates. I like how Luffy isn't pulling any punches and taking care of business. Also they have become really suspicious of people.