Yes, if I don't want to see illegal content I'll block the account. But the media is remains on the place.
And if you rely on the authorities, you also rely on the state, and this is not the case why Nostr was created: the freedom of speech.
I think we cam find an "automated" solution. E.g. only an idea: different nodes (relays) examine the incriminated media object and decide by voting about it whether it is illegal or not. It is not a new idea e.g. the NEO token's dBFT mechanism does the same as I wrote. Simple byzantine generals problem