I've kept rats my whole life and on one hand I'm not surprised, they'll eat what seems like literally anything, on the other hand they seriously pick their battles, a rat isn't going to engage with anything it's unaware of, they have extreme neophobia so I'm somewhat surprised this rat felt the situation out enough that it was comfortable doing this, I'd guess it had spent a lot of time around the bats, also surprising because the rat is a bit on the chonky side to be opportunistically hunting that way. Interesting.