I think it was a good distinction to point out that as a general rule tasers should be used to prevent someone from doing something and not to force someone to do something.
First: I tend to agree with CC and Marmot on this one. Don't want to get tazed/restrained/beaten/arrested? Don't do mind altering substances at a public event and get naked. Simple as that.
WRT prevention/force: So far everyone has overlooked the fact that, in these types of situations, you don't have time to pause and reflect whether or not if this force is necessary or not. I don't think any cop has time to reflect and say, gee, well, this guy may not be responding to reason, direct orders, maybe I should wrist lock him first and then taze him second. They are not trained this way, nor should they be.
Finally, regarding the folks who submit that 'nudity is not a crime,' the fact is (a) it is a crime and (b) there are plenty of other nuisance crimes that make life unpleasant for those subjected to them.
Would it have been OK if he squatted and shit? Pissed? I mean, he's not hurting anyone with those actions either. How about if he started jerking off? Stuck a finger up his ass?
What about playing your car radio so loud it wakes up the entire neighborhood at 3 a.m.? No one is getting physically hurt, no, but it's stilll illegal to do that in my city, to the tune of a $300 fine. Just becasue we have "freedom of expression" doesn't automatically mean that all expression is legal.
People, we live in a society. If you are not going to submit to some baseline norms in that society, you are going to pay the price. In this case, drugs+nudity+crowded festival=tazing.