Good point, it does not appear to be a sealed connector so that could be a factor. The GMRS-V2 is spec'd as IP54:
5
Protected against dust limited ingress, no harmful deposits.
4
Protected against water splashed from all directions, limited ingress permitted.
It seems like it might conflict with that rating as-is, not sure what the acceptance for "limited ingress" is though. They could probably throw in a cheap silicone dust plug to get it there. I might pick up a couple to stick in there for hiking (that I will eventually lose). Most of the other compatible radios with the BL-8 don't claim any sort of IP rating though I don't think...
It did eventually go green when charging. I checked if it was bi-directional to use as a backup battery for other devices (charge a phone from it), it is not.