If they're just a post-and-run Troll, then, by all means, hammer them. But if they stay to argue .. to, at least, try to stand their ground and compete in our sandbox, then let them stay (at least until they reach the "so's your old man" level of argument).
Besides which, it's fun to watch Dighton hammering them in Latin, Norwegian, Esperanto, Congolese, and whatever other language posts he can dredge up that remotely pertain to the subject being discussed.