There's quite a few ANR headsets available that advertise Bluetooth connectivity so I doubt legality is an issue- I think the law regards transmission/reception from a base station. Bluetooth only has a range of about 10m on those types of devices so that isn't a problem. I doubt it would cause any audio interference either.
I think every 152 I've been in has at some point had a 12v car-style socket but I don't know if they all do.