I've seen several cases like this on Amazon, where products are not available to ship to California but should be. In one case I even spoke to the manufacturer who said they got it fixed, then weeks later it was unavailable again.
There's clearly something going on where their systems are being extra cautious on what can and cannot be shipped to CA.
I don't think that's true though? The OAuth provider knows which third parties you have authorized to have access to your account(s) as well as what information or privileges you've approved for each. And when you land on that screen, they know which third party referred you to them.
In other words, they could definitely highlight or otherwise hint to you which of the Google accounts you've already approved/used via one or more of your authenticated Google accounts.