What's wrong with calling someone Mongo? Have none of you seen Blazing Saddles? Big daft brute with low intelligence causes mayhem and nobody can stop him. But he was easily outwitted by the hero.
Context is everything.
Likening Tevez to someone with mental illness/disability is surely more offensive to Tevez than to people with mental illness/disability? And that's the point.
Except Tevez probably doesn't come on here, so that's the counterpoint.
This forum is not the place for it.
Incidentally, Mongo turned out to be a good guy in the end. Although Tevez has been outwitted, he's unlikely to turn out to be a good guy. You never know though. If nobody wants to buy him, he might suddenly realise Kia is the debbul and fuck him off.
So perhaps Mongo is the best thing we can call him.