Definitely a failure on the parents there.
However... your party was guilty of not asking earlier and then perhaps guiding him on the fact that he wasn't really tanking.
Is that how long it took to ask why you guys were getting run over the coals? A bad tank is immediately obvious. One that was blowing chunks that badly should have been an indicator that something wasn't quite right.
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Grimlik Amberdrake
Current game: Real Life Patch 2.0
Sheep Slayer
Waiting for something new and inventive and fun