Hudson is the closest to you licensee on this frequency, but it's licensed to the PD. Worcester still holds a license on the frequency, but I don't think it's active. It seems to be licensed mostly to PDs, not FDs.
I don't have any information, but it does make sense. Cambridge has UHF patches to some TGs on it's trunk system, in the name of interoperbility of course. Maybe Worcester is doing the same thing.
Not related, but the Boston PD channel of the same frequency is their mobile ops channel. When I lived in the city it was my priority channel. It's hit or miss, but Friday or Saturday nights always had something good going on..I miss that channel the most since I moved farther from the city and can no longer get it