Wow, sure hope they're doing some screening.
I see they're getting around public nudity laws by billing the event as a protest — in this case, for better cycling safety.
Pretty scary if you ask me. Living in a beach town, at least 75% of the thong- and Speedo-clad beachgoers I see are committing blatant acts of disregard for public safety. You just can't unsee that stuff.
Of course, I'd be in the 75%. But I care too much about my fellow man to do such a thing.
For similar reasons, I don't wear lycra.