Recently the USA blew out some some boats in international waters and came back to finish off the survivors, despite thin evidence and no due process, while maintaining that it was legal. If those data centers on ships ever become declared as a 'threat to national security' then they might get the same treatment.

I think GP's point is that an advanced nation-state could just as easily shoot down an orbiting data center as an oceanic data center and that "international space" offers an equally flimsy defense as "international waters" but a much larger price.

This would be equally true in space.