Agreed, but at the same time it would also be worthwhile to look at ways to increase our detection and policing of shipping around these cables. I'm no expert but I imagine there are ways to speed up naval reaction times, tighten penalties for ships going dark (transponder off) and set new policy norms enabling rapid investigation.
Basically things that make it harder for bad actors to maintain plausible deniability. So far, a lot of this has been done with relatively low cost and low risk for the perpetrators. The fact this Chinese ship was chased down and stopped before getting too far away was actually pretty lucky. If we formalize new systems and policies to ensure the instant a cable is cut there are navy ships converging on suspect ships - that will shift the cost calculus of the bad guys. If every cable attack requires a special submarine deploying a demolition team underwater near the target, it gets a lot more expensive and if caught there's little deniability.
If these kinds of attacks continue then I expect we'll see some extra-judicial direct action consequences imposed. Like a ship that gets away later having a mysterious accident causing it to slowly sink in deep water (thank goodness another passing ship was nearby to rescue the crew!). While I don't like it, when bad actors figure out a way to repeatedly avoid consequences, sometimes a little rule bending is needed.