On ACR, I haven't seen a option to block a person's chat while they're still at the table, but you can turn off observer chat once you've felted them.
Seemed to me the OP was regarding beating a player. I am, more than I should, prone to "giving him the business" once I'm out and gone. Did this again recently when a guy called my 4x BB raise preflop with 3q when I had KK. He was in early position and I think I was one of the blinds. The whole play makes so little sense to me that I blow up Matusow/Hellmuth style. I don't get (or can justify) even his initial limp with such garbage. Then, to call multi-way with a pretty good size raise preflop is ONE thing. But then on the flop, when he hits a 3, he now calls (max bet tech) 2/3rd pot for most of the rest of his remaining chips. I wasn't really going after him, but the others with more chips when I bet like 1.2-1.5x pot to put then all in on the turn. He was the only one who called because it was a 3. He laughs at me the whole time and suggests he is a superior player. I'm not really bitching about play like this. By all means, try it all day, we'll see where it gets you. But I was super pissed at the time and made it known.