Blocking all these accounts is impossible. And you wouldn't necessarily have to be looking for anything to see it. And it really isn't just a matter of some nudes or porn. Depends on how you use nostr. Really this is mostly a Global issue and maybe a relay thing.
I *suspect* that there could be some people who may be slightly naive about some of the content/users on nostr. You could get the impression that it is just a bunch of Bitcoiners having a laugh (it mostly is), when there is some pretty grim stuff out there.
I'm not saying the person who mentioned this is like this, cos I have no idea, nor you. I'm just saying it's a possible scenario