It's not a political ideology or political speech. The reason we came up with freedom of speech is primarily so you can criticize the people in power. I know that people for whatever reason got this weird idea that pornography is somehow free speech, presumably because of lobbying, but historically free speech always coexisted with obscenity laws. If you want to silence your political enemy, it's going to be hard to do on the basis of pornography, but it's rather easy to do on a basis of 'hate speech'.

I don't really consider that censorship. We made it illegal to exploit minors that are unable to make decisions for themselves (both legally and maturely).

Then, at the arbitrary age of 18, we (the US, other countries differ) decided they can participate in, create, and distribute as much self-pornographic material as they want.

The entire LEO world dedicated to combating child pornography revolves around the exploitation of children and how wrong that is.

That's not quite the same as banning ideas, books, etc, simply because some find the words objectionable.