How about: "Websites shouldn't do digital fingerprinting to intentionally circumvent incognito mode." Does this make sense to you as a legal argument?

And yes, this does mean that if it comes to litigation, a lot of this will depend not just on what you did but why you did it.

If you write analytics, unaware of incognito mode, you're probably okay.

If you write that same exact code because your boss comes in and says "shad, we're losing A LOT of user data to users in incognito mode. Could you do some kind of digital fingerprinting so we can still track them?" then you might be criminally liable for digital trespass -- you've intentionally bypassed my security mechanism.