A country throwing vast amounts of resources to train elite units, equivalent to millions of USD each, and throwing that unit away at the drop of a hat? That seems extremely suboptimal just from a resource perspective alone.
This seems similar to the optics problem of people thinking Roman gladiators killed each other, where in reality gladiators were essentially MMA and rarely heavily injured each other due to the loss of resources, let alone killed.
I think there's some of the inverse as well. Insubordination and military prisoners in the ancient era often led to summary executions. People confused foreign stories with combat sports.
Combat sports, ceremonial fighting, you're right. Losing talent was rarely worth the propaganda.
In the field, risk factors are cut off violently. Prisoners have value, especially ransom. Risks to the command integrity may have more value
dead. Morale and resource management can involve public executions or decimations. At sea a prisoner hurting morale is even worse. Killing your own side or any prisoner is stupid warlord tactics or child soldier training, but the ancients used the same stupid reasons.
Anyhow this chapter handled (in)justice well imo. Evil empire coded, within reason. The young knight's career is done. What's the alternative from clone/bro's Cpt perspective? Lie in your report that this Sgt you respect didn't disrupt tactics repeatedly? Bring her back to get tortured and starved or executed, maybe experimented on? A suicide unit may not be feasible for a while. The country clearly isn't set to let (supernaturally) talented zealots fester until they become security risks given they disposed of lagging child soldiers. (Well that part is unreasonable but Cpt's acts make sense given the idiot government.)