Tobacco is the analogy, you don't want to see people smoking on TV and in films but you would not want a documentary on the history of film to be banned just because some of the actors in it are smoking.

Regarding main story, I used to work in broadcasting and it was clear from the oscilloscopes when some porn was on air or on a tape. This was not an exact science, but experienced engineers knew what the 'scope was telling them. This was a long time ago and I am sure Google would have machine learned porn a long time ago. No evidence for that but I doubt it is a recent innovation.

Therefore this enabling of the feature that enforces the Terms of Service is probably due to changes up ahead in the legal landscape and not because Google suddenly decided they wanted clean servers.