If you haven't addressed the assistant's behavior by now, I agree that you're going to have to live with it in the 4th quarter as long as it doesn't suddenly leap across the line.
However, if the whole bench is up over a percieved missed T I don't think you can single out just the unwarned assistant for being part of the mob. If this is the first time they've all been up like this, I'd have the "get your bench under control" chat with the HC, which is how I'd handle it if it were in the first quarter. And throw in a, "Especially your assistant" just to get that taken care of.
But even if the mob rose up again, I would still be loathe to tag just the assistant. Now if the assistant started chirping...
