The point there was to make sure no scholar from Ohara escaped. Sure it was inhumane to act in such a way, but it accomplished what they set out to do faster and with more certainty, didn't it? As if the concept of slaughtering all the scholars in itself was something very humane to begin with...
He was a vice admiral then, and inspite of that, he was still promoted so clearly his actions weren't wrong enough for the higher ups to give him the leadership role of an admiral.
Having fearful troops is actually a bigger problem than you think. Troops routing from the frontlines can disrupt the morale of others holding their ground and cause a chain reaction of fleeing troops. Yes, its an monstrous thing to do but I wouldn't call it tactically incorrect.Because he's psycho. PSYCHO. He was killing foot soldiers that were afraid during the WB war. PSYCHO. What was even the point of that? He was just wasting time doing that!
Ruthless, dictatorial type figures can actually make good leaders for MILITARY ORGANIZATIONS despite having a shaky moral core.