At the very least because she’s smaller than her “Dad.”
Because it sounds so nice and fluffy to someone who doesn’t know the awesomeness of the Honey Badger.
But isn’t that Laura’s thing though? Opponents that don’t know her automatically see a little girl/tiny woman and are like, “Whatevs. I got this.” And then her claws come out and she ruins their entire lives!
I can imagine that becoming her nickname among the other New X-Men. It probably was Santo’s idea.