I imagine people do get their knickers in a twist.
I think a lot of people now have been taught a very reductive concept of human sexuality. Just this: it's innate, unchangeable, and you are either attracted to one sex, or both, and those three permutations are described using certain words.
That's been the main narrative since I guess the 80s. It wasn't the only or even dominant narrative before that, including among many gay and lesbian people. It's also notable that it's not a scientific perspective, it's closer to an ideological assertion. It seems to describe some people's experiences, but not others.
From a sort of anthropological perspective we can see that culture strongly influences how people experience and conceptualize their sexuality, and what they do about that.
I would also say that for many adults, they can see changes in their sexual attraction over time, even up into old age. Smaller usually as they get older but not always. The idea that we are totally fixed doesn't seem realistic.
Given all this, I think it's reasonable to say words like lesbian can be mainly about what a person does, rather than some internal set of feelings - though obviously these things will often be related. If JB never has relationships with men, even if she is theoretically capable of sexual attraction to one, is there much point in calling herself bi-sexual?
And I think that approach has historical precedent too.