Sure. If you're going to boycott the movie, then I assume you will find out where he eats, shops, gets gas, etc. And boycott those places as well, right? Crap, he likes tacos? Guess I'm done eating Mexican food.
Not anywhere near a logical argument. If Singer made me tacos, I wouldn't accept them. If he owned Taco Bell, I wouldn't eat there. But the fact that he might like them has no impact.
Singer was the DIRECTOR of this film. That's the CEO. The guy in charge. Totally different than what you're trying to argue.
People need to think a little more about the outcome of their actions before doling out punishment. And this is all assuming he did anything wrong - Singer is being viewed as guilty until proven innocent.
Apparently the fact that he throws these annual parties is not disputed. The idea that he throws annual parties that focus on child rape should shock anyone. But in Hollywood nobody raises an eyebrow.