[voyou]

"company are now choosing to, by default, have sexually explicit content blocked"

But that's not what they're doing. They are choosing to block a wide range of material, some of it pornographic, some of it educational, some of it merely to do with gay and lesbian identities which some people find immoral (or to do with the occult, or computer security); and also to not actually block a lot of sexually explicit material that slips through the filter. And they are "choosing" to do this because Cameron said he would legally require them to do so if they didn't do it voluntarily.