This is what the rules of that instance say:

• No illegal content under Netherlands law
• No content involving junior idols, child models, or anyone under the age of 18 in revealing clothing, questionable poses, or questionable situations

I also dont see any pedophelia on the frontpage. If you do, try contacting the admin to remove it. Of course you are free to block it from your own instance, but its a really flimsy reason to delist it from joinlemmy.

Loli is legally considered as paedophilia in europe and the US

It isn't though. Legally there's nothing to be done about it. Defederation and blocking it from the main list is certainly advisable, though.