Thank you for pointing out my mistake.
I was not aware that the adult search option would still be there without the setting. I do know from experience that it isn't there if you aren't signed in though. That said, I don't think parents should be allowing their children to get accounts or even wander unsupervised if the parents don't trust the children to use their own judgement on what is an isn't allowed for them. The fact is uncurated indie games can have arguably worse things in them than nsfw content (such as outright propaganda). As such, I think publishing games, especially horror games, should really only be done by adults to begin with, so that issue with the adult setting is not something I'm concerned with.