If you've got tape handy, might as well tape over the hole. Of course, I think our area is about to get hammered with some rain/thunderstorms (tomorrow and Monday) since I washed my car last night, so the tape might not last. I'd still probably tape it if it were me.
I had a small fender bender last year that took down one of my parking sensors temporarily. Like yours, there was no actual damage to the sensor, but the flex in the nose cone (or bumper in your case) was enough to smush the wires leading from the sensor to the rest of the car. Easy fix for me, just popping off the nose cone and repairing the wires. Yours might be a bit more involved.