Yeah, that's a Bandcamp thing. The Licence file in the download clarifies that it's CC0.

Given that your case is likely to become high profile, you might want to drop them a note to add CC0 to the list :)

I'm only guessing, because I don't have a Bandcamp account, but usually media content hostings have a limited choice of licenses, so people pick whichever license is closest and mention the real one in description. I know this is true for e.g. YouTube which simply doesn't have the CC zero option.

Makes sense, thanks.