I would say your actions were justified, based on your description. You could have been gentler with him/her, but I was not present and it's probably a bit much to expect you to deal with someone else's problems. Your superscrub guest has the worst k/d for PvE events I've ever seen, with 4 level 34 characters. Judging by his record, he's been through raids as a dead weight, and even Trials of Osiris, so by kicking him late, you probably saved some other team from carrying him for an hour.