Legal methods are a crutch at best. Apple would be wise to put forth the same budget into their security team's research and development and properly address these weaknesses.
The attack surface of software as complicated as a modern operating system (iOS or MacOS, etc.) is simply too large to lockdown without dramatically hurting the user experience (assuming you could actually achieve a lockdown in the first place!!).
Let’s, just for a second, propose that apple went full Monty and locked the whole shebang down with the kind of tech they’d need to resist NSO. That’s more custom silicon, signed binaries everywhere, even fewer per app permissions, literally treating any piece of software running on the device as a potential threat vector even more than they already do. What would this get you?
The BoM cost would go up, a lot. The cost of writing software would go up, a lot. And perhaps worst of all: it would only raise the cost of a chain of exploits, not eradicate it.
Right now a chain of exploits is ~$5M on iOS. What if it was $50M? Would that actually stop a nation state?
I’m sorry but there’s no world where Apple can make perfect security.
Finally, the cost of this lawsuit is a drop in the ocean compared to what they already spend trying to secure the software and hardware in iOS devices.