IMHO we don't have enough background to speculate on personal traits of the OP's adversary. (Perhaps nobody is intending to do that, it's just good old thread drift... oh well.)
Yeah... we don't even actually know that the guy in question WOULD have any problem with not getting his next rank soon; that's just speculation. For all we know he would be totally fine with it and respect his teacher for telling him to wait. So a lot of the conversation is not really specific to him.
Regardless of what's going on in this particular situation, my experience is that if you expect the best of people they will often rise to the occasion.