Come on, Dave O and Martin.

If you are a concert promoter, do you really expect an artist to do nothing but sing songs? Do you really think the performer is obligated to not say anything that might offend anyone in the audience? Do you really think that "I paid to be entertained and this did not entertain me" is an excuse to THROW COCKTAILS?

Honestly, that's ridiculous. "Arrogant misuse of the position?" It sounds to me like a few people in the audience decided to arrogantly misuse their cocktails in order to shut someone up with whom they did not agree.

As for "free speech," this was a principle before it was a law. If such actions as this do not violate the law that doesn't mean they do not violate the principle.