I think the linked piece makes an important point, but I disagree that that point is relevant here. "Your argument pattern-matches to tu quoque" is probably an unhelpful thing to say, but what GP says is more like: "Your points about other people are not relevant to the discussion we were having out this one person, and therefore are unhelpful. This pattern of bad argument is sometimes known as tu quoque." Seems fine to me.

Edit to add: not sure if I am alone in this, but I also disagree with the author's characterization that the purpose of thinking about fallacies is to understand how people come to wrong conclusions. I think it has much more to do with the structure of an argument. It's not "you have come to this wrong conclusion by treating this fallacy as a good argument". It's more like "you believe this for whatever personal reasons you might have. You are trying to convince me to believe it as well, but you are failing to do so because your argument is not valid". I.e. it is more about the rhetoric than it is about coming to wrong beliefs in the first place.