but for the life of me I can’t get inside this type of person’s head space.

My guess is the bottom-of-the-barrel people willing to sign up to be ICE contractors knowing what the job is have previously been powerless and ignored before in their lives. Signing up with ICE gives them a uniform, a badge, limited authority, and a weapon they see as a means to force people to comply with their authority.

So when a pair of unarmed woman called him out for what he was, ignored his perceived authority, and were not intimidated by his uniform and badge, he used his state issued weapon to enforce his version of authority by shooting one as they walked away after they had emasculated him. He couldn’t [let them get away with it].