FYI...

Closing a door takes more time than opening it precisely to limit the effectiveness of such a tactic. Even vs. spamming or a trigger you always have a reasonable chance to open the door and get through it before it's closed on you again.

That said... while it's certainly not inappropriate to sass a groupmate who's being rude to you, it's also not necessarily inappropriate for that groupmate to try to get his revenge. It's expected that there will be players outside of your PK range that will be your enemies and try to assist in your death. If you continue to play, I think you'll find that in most cases the effect they can have is minimal.