Legal concepts can be complex, and location specific. We may be drifting a little off topic getting into legal concepts.
I'm no lawyer, but IMO, there's a reasonable expectation that if you pay for a dive with a "dive master" (or "guide" as I call them), that this guide should render assistance if they notice a diver having trouble. I'd probably even say it's reasonable to expect some kind of dive-rescue training.
The dive-community overwhelmingly thought both cases were absurd. Myself, I considered it logically contradictory to suggest buddy-A was liable to successfully rescue buddy-B, but buddy-B wasn't liable to buddy-A for getting themselves in a situation where they needed rescue. So far, thankfully, that appears to be only Malta.
There were 2 absurd legal cases out of Malta, where a diver died, and their buddy was charged with manslaughter (or a relative equivalent). The basic facts of both cases were essentially a the buddy was unable to perform a rescue or didn't know the buddy needed rescue. The buddy didn't do anything which caused or contributed the death. If I remember correctly, one was "Stephan Martian" and the other was "Castillo."