I categorically reject that assertion. Two simple examples: 1) when you see someone assaulting someone else, it's absolutely ok to attack them, and 2) the American revolution!

It's like that old joke:

A man offers a young woman $1,000,000 to sleep with him for one night.

“For a million dollars? Sure, I’ll sleep with you.”

He smiles at her, “How about $50, then?”

“How dare you! I’m not a whore!”

“Look, lady, we’ve already agreed what you are, now we’re just negotiating the price.”

Similarly in this case, you can't make up absolutes and assert the're true, while ignoring that the real world is more complicated. And once you do realize the world is complicated, you realize there aren't absolutes: everyone is a prostitute, terrorist, or whatever other bad label you want to throw at them ... it's just a matter of degree.

So no, it's not always wrong to physically attack someone like this. You can debate specifically whether Altman has committed enough violence himself to justify violence against him: that's something two people can reasonably disagree on. But you can't just say "violence bad" like its some great pearl of wisdom, while ignoring that violence has in fact been good many times throughout history.

It's always OK to punch a Nazi.