During the 1st world war many commander died by their own men for less than this. You NEVER EVER antagonize the dude that you are fighting with, it's literaly the same as killing yourself. And beating the healer because she tried to save her friend from a grenade?
Yeah no, this dude would not survive a single day after this.
You are basically trying to stab the devil in the back knowing he can fucking cut bullets with his sword and is one of the top 5 strongest fighters of your entire country and keeps surviving bouts with death every day despite leading from the front, being always the first to go and last to retreat while his soldiers that are basically following him are croaking left and right sometimes in a matter of days after they are being asigned.
Even if everyone under his comand atacked him they would end as corpses in a matter of minutes, they might not like his ways but acting against him is suicide and they know it
To compare Garback to a normal soldier is like saying that a Space Marine is just a bit bigger than a normal human wearing tin can armor
You can be a complete arsehole, but even with all his spouting, he is really lowering the efficiency of his men using excessive violence. He is not a commanding material.
And using the greatest amount of violence on a young kid of all things? And it is the bloody medic?
Yeah no, he is complete trash. He is good at fighting. He is not good at anything else.
He should never be someone that holds a commanding position. He is as incompetent as they can get in that field whilst still being competent soldier.
If our protagonist was more malicious in nature, she would gradually wait for a chance when he gets critically hurt and look him in the eyes and tell him she would treat him like he treated her, like trash.
I agree that his teaching methods are wrong, but hes in universe acknowledged that while hes a great assault commander he would be a poor general, something that has hindered him at climbing ranks, but doesnt get bothered by it.
Remember despite his losses he actually gets shit done compared to other squads that also have losses and barely do anything too risky something that happened for example when Garback was forced to retreat because his allies didnt follow and they lost the gained ground as a consecuence
About the child issue, in the setting for good or ill shes just another soldier as as we saw the enemy considers her one as such as well not caring for her age nor gender
The protagonist have an inusual good common sense for a MC, so she would never try to goat in front of someone who would atempt the last laugh and probably had very good chances of suceed even on the verge of death. As much as a jerk Garback is his teachings will help her to keep herself alive