Maybe they could at least run a 24/7 FM translator from that, if they can find a frequency.
Even if there were somehow still an available frequency (there is not), an AM station can't just apply for a new translator. There were a series of FCC filing windows, the last of which closed in 2018. Once they closed, the only way for an AM station to get a translator is to buy an existing one, if one is available. That's a very expensive proposition in Boston.