I have no doubt that if your proposal were to pass that there would be significant efforts from extremist conservatives to censor LGBT+ communities online by labeling sex education or mere discussion of our lives as pornographic. How are LGBT+ people supposed to live if our very existence is considered impolite?
Nevermind the fact that the existence of a government database of all the (potentially weird) porn you look at is a gold mine for anyone who wants to blackmail or pressure you into silence.
The horrors and dangers of porn are squarely a domestic and family issue. The government does not need to come into my bedroom and look over my shoulder.