It will likely depend on how popular Lemmy becomes as well as the server physical location \ DNS registry that of used.
Having a piracy channel on an instance located in a country that does not recognize intellectual property, and a DNS registration in a TLD that doesn't respond to piracy complaints should be pretty bullet proof. Only thing that companies could do at that point would be to try to get a court order to have the DNS entry blocked by US \ EU \ etc DNS providers, or a court order for ISPs blocking the server IP address. These could be easily circumvented by changing the server IP if it happens and updating the DNS.