Not to sound mean about this but...if someone starts complaining that I accidentally lost ONE mob to overaggro and suddenly they get all pissy, I simply tell them to replace me.......I mean it's not like there's a huge lack of tanks right?
Seriously they should be glad a tank is able to, well, tank and survive, more props if it's able to survive and help the team in crutch situations.
But complaining for silly reasons requires silly measures, so I hope they'll enjoy waiting in a queue for X minutes and possibly ruin their run because "of that ONE single mob that he didn't aggro JUST right"
But in all sincerity, as long as your team DOESN'T DIE - no matter what the reason - this kind of discussion is to be mandatorily ignored. You live? good, now move forward.
If you let them die then, well, that's a different story.