A lot of cops are so high strung that you essentially have to pretend you’re having the time of your life while interacting with them - any nervousness or annoyance is taken to mean that you’re potentially a violent criminal who could kill them at any moment.
Just the realization that a woman holding a pot of hot water could hypothetically use it as a weapon, however unlikely it was in this scenario, was enough to make him instinctively shoot with only minor notice that still did nothing to prevent him from killing her even as she began cowering and apologizing.
This is the culture we’ve allowed the police to build in this country; the job is dangerous, and they’re only human, so they believe they should be forgiven for being scared regardless of the situation, and should be forgiven for taking drastic measures while they’re scared.