I think the idea is that Rachael was being careless by not trimming her nails. Since people are very fragile compared to what Rachael is familiar with, she needs to be extra careful to avoid killing or seriously injuring someone.
Going the domestic violence route in response does feel mean spirited. The execution is similar to the older "violence against boys is funny if a girl does it" trope, where the idea is that they couldn't really damage the boy physically or emotionally. There is a similar physical power imbalance here. It was never a good style of humor, though. I don't care for it here either.