Interestingly enough, I think this isn't on Ghosty at all. Ghosty should be upset about he was treated, and the fact that it still bothers him is clearly a function of how his community conspired to minimize the trauma he experienced for being abused.
Clearly the teacher is repeating community-created rules as to when and where airing of grievances is acceptable, taking away Ghosty's ability to address the trauma in his own way. You're certainly right in that, with most situations, allowing past trauma to haunt you creates situations where the attacker increasingly gains unwarranted power over the victim the longer the trauma festers. In this case, though, Ghosty's inability to address the problem at the time is immaterial to the repeated trauma of him being suppressed, inflicted not just by those who were suppose to be helping him but by all those who stood to benefit from his trauma being squelched. Furthermore, the fact that it still bothers him is at least in part related to the fact that resolving the trauma is exponentially more difficult when it's a function of a conspiratorial conglomerate rather than a single act by one or a few perpetrators.