Holy crap, the kaboom teacher's a freak.
And I imagine that, as inhumane as it may sound, those golems were probably designed to scream when injured as a means for students to numb themselves when facing dire situations, such as comrades critically injured right in front of them. When in the battlefield, there's no time to hesitate, and you may not have a chance to relocate the victim to a safer spot for the treatment, so you'd have to act quickly.
It's no wonder those in the healing units get paid higher as it takes serious mental strength and fortitude to be constantly exposed to such gruesome imagery on the daily.