If that bagel shop will ship bagels to UK soil or accepting money from UK citizens who are currently in UK as 4chan does, it will be subject to UK laws regardless of whether it has legal presence, assets etc. This is not matter of jurisdiction as some of commenters here believe.

UK has limited enforcement options, of course, but it’s their sovereign right to prevent illegal activities and/or punish for them within their capabilities. This is why 4chan lawyers are asking for political response as if UK were a rogue American colony.