Is there a term you would prefer to see used over “adoptable”, such as “homeless” or “rescue”?
It shouldn’t be offensive at all. “Adopt” means to “take in”, and is used in many instances (like “adopting” a dog, child, highway, or name/idea) and doesn’t usually refer to the thing/person/animal being taken in.
I can’t even think of another word with the same meaning as adopt.
I was having difficulty finding an alternative word for adoption that accurately describes the process, as well. Although I don’t believe it is fair to dictate what is and isn’t acceptable to take offense to, particularly in the case of triggering subjects; unless some genuine concern arises from the individuals that do find the term offensive—and I’ve yet to receive a complaint thus far—I think we’ll continue to use the term, for sake of ease.