but how can you remove adult-only features for children only without knowing the age?

They're saying we should remove the features in general because they're anti-features harmful to everyone, and focusing on children distracts from that fact.

This conclusion is up for debate, but that's what they mean.

We should ban oil, drive EVs, everyone write Rust only, and invest in index funds. We should, but it's not going to happen.

don't do harmful things is pretty easy and can apply to adults too!