Yah, I don't think restricting access to self-described porn has all that many downsides. Governments that would do that, already restrict it, this just makes it easier for them, but the benefits to parents far outweigh that.
This is not the same as general purpose censorship, which I do not think should be made easier to censor.
Do remember that someone in a different (more permissive) country voluntarily described his stuff as porn. So you don't really have an issue of it being applied incorrectly.
