Well it seemed to me he felt a bit weirded out. I don't think he's that well traveled. lol, so running into otaku culture seemed to make him realize a couple things over the course of his trip if you watch some of the interviews after the fact. But I think he got lost in the moment with so many people wanting their personal photo of costa doing a costa thing.
He mentions it in https://www.youtube.com/watch?v=CVDeFYSabH0
When you're a guest, it's sorta impolite to refuse. I think he did the right thing, they brought him over to do exactly what he did.
Even the people who did know it was airsoft, they still ragged on him for misrepresenting firearms safety... I dunno, when you're in a different culture and they are perfectly fine with what you're doing, what's the big deal if you are able to differentiate between the 2 worlds of real firearms and toys.