Hey Julie!, i'm a journalist too, and we all have different ways to approach people, this guy seems that he is going to do what he is going to do. Airbnb makes it imposible to reach hosts if they are not wanting to book your place, so he said that he needed to fill out as he was going to book a room, even tho he didn't, and he just ended up doing an inquiry.
Maybe he doesn't know anyone related to that field, and you just randomly appear, ask him if he can proove, that he is a journalist, we have to be really caferull about what kind of questions are we getting asked. but as he said.. it can be by email or phone, so it sounds really safe for you. People who are not related to our field, think that we might be scammers or something worse, because we do a lot of questions, but at the end of the day that is our job!, reaching the correct person in anyway we can.. and that's what looks that he is doing with you!
So if you want to help a journalist go ahead 🙂 if not, then decline it politely and he will understand!.
I don't believe there is need to reach Airbnb.. because they do have other more important issues, than just this (and i don't mean it in a rude way at all)
Regards! 🙂