I don't think he has fear as much as it is a cost benefit analysis.
What do I gain from punishing Tyreke? His answer may be: He thinks before the next time he does something stupid. But just the next time
What do I lose? Answer: A huge downgrade in overall talent.
Like I said, if Monty thought he could change Tyreke, I think he would sacrifice a few games for the long run. But I think it is kind of naive to think you are ever changing that guy. But again, that is my personal opinion. Hopefully he proves me wrong. But I doubt it. I think he is who he is, and that guy can be a major piece on a really good team as a pace changer off the bench.