This is going to sound super scummy, but honestly they deserve it. Lately, whenever I encounter a player follower dungeoning, I open up my second account and create a new character on their server and faction. Add character name to regular friends list to track them. Create a macro and in it, include /invite player-server.
Now whenever they’re out of the follower dungeon and people are attacking them, spam the macro. Fun fact, players can’t queue for follower dungeon if they have an active invite, it won’t allow them to queue.
Works like a charm and they die. Again, might sound overkill and scummy, but they deserve it. 