Smith, I believe, likes a lot of the Catholic church's tenets, but not all of them. I don't know exactly what he rejects, but I assume, say, the ban on condom use is one of them since he doesn't have a million children running around in shorts and trenchcoats.
I could be wrong, but I thought one of the core beliefs of Catholicism is that the Pope is your leader and what he says is coming directly from God and he's infallible, etc. But if you call yourself a Catholic and you reject this, are you really a Catholic? I'd think you'd need a new label for yourself.
Just like someone who calls themself a Marvel Zombie, but no longer likes most of what Marvel produces should stop calling themself a Marvel Zombie.
And sure, language is alive and word meanings can change. Over time, I'm sure a label like Catholic can come to mean something different. But I'm talking about words as they're known now.