The crowd is egged on to boo the baddies and cheer the heroes. All this is great. The people filling the seats can decide on their own whether or not to take part, or just how far they'll go. Then there are Nausea and Alopecia, Cinderella's evil step-sisters, played by Nigel Gore and F. William Oakes. They fight back and individual members of the audience have no say in whether they'll be part of the action.
Participation becomes assault.
I, and others, were also mauled by Nausea and Alopecia later in the first act. That I didn't enjoy. The line was crossed. I had no say in whether or not I'd take part. Suddenly my space, the theater seat, was violated.