It’s in the Irish EEZ, which means it’s navigable waters for everyone, but the Irish can drill for oil or put down undersea cables. The “escorted away” thing legally looks like as when someone wants to break into a store and is walking around the storefront with a crowbar, and police come out and just observe and deter the likely perp until they go away.
They can’t tell the vessel to go away, but they can put a few proverbial spotlights on it so it doesn’t do things it shouldn’t be doing.
Oh, BTW, this is exactly the sort of situation that goes down again and again in China, except there the Chinese actively ram ships and endanger aircraft in their EEZ.
The DMA has no bearing on disinfo, it’s about access, like mandating a public API to federate with or banning self-preferencing with other products.
The disinfo thing is regulated by the DSA - Digital Services Act, and it very much applies to Twitter.