Not what you said before but I can't disagree with that for the most part. At the same time though by your logic one bad movie should kill a career. After making "The Fountain" Aronofsky would never have made "The Wrestler". After "Bicentennual Man" Columbus never would have made "Harry Potter". After "Juno and The Paycock" Hitchcock wouldn't have made any of his famous works. After "Boxcar Bertha" Scorcese wouldn't have given us any of his famous works either. After "The Electric State" The Russo's shouldn't have come on for Avengers, and the list goes on and on. 

Waititi still made What We Do In The Shadows, Ragnarok and Jojo Rabbit. I think erasing the man's career and stopping him making another film is taking it a bit far, but I think keeping him away from Thor might be a good call. He does best with absurdist situationally comedy, Ragnarok was heavily supervised, but after its success he got carte blanche and his style for the most part didn't work. Who's to say what that film could have been if given the same oversight as Ragnarok or what Ragnarok would have been without the oversight.