Yeah I think it had something to do with the protagonist not being a morally gray character and/or not having to make an ethical decision... it was something like that. I should listen to it again, except I know I won't (I don't think I've ever listened to a podcast twice). There's also a fairly common feeling that "true" noir is American, although most make an exception or two, especially for Third Man.
At any rate, it's my #11 on my list, so it's noir to me.