Disclaiming Banner: I don't own ATLA because purple platypus bears aren't allowed intellectual property rights under our oppressive international copyright laws.
Benignity
He didn't hate the other monks, not even the Abbot for trying to take his beloved pupil away. Truly he did not for their actions stemmed from fear. Fear of war, fear of attachment. Gyatso understood this; human beings are weak against fear. Firelord Sozin was fearful. Roku's life-long letters to himself made it clear the man was driven, obsessive, and increasingly cruel.
No he did not hate the other monks for fearing the repetition of those war-mongering Fire Nation colonies from two decades before. But he would not forgive them for the way they struck Aang out of the sky.