In fiction, it's the writer's responsibility to give reasons and explanations for things that may seem absurd.
The fact that many people ask about the California-Texas alliance goes to show it's confusing to people. A good writer could have added on sentence to fill in the blanks. It's a big plot hole for many people.
Yeah the minute I heard “the Texas-California coalition...” in the trailers I said to myself “skip it”.
Absurdity can be a literary vehicle itself. A person from California may say “People in Texas can learn a lot from us due to our intellectual superiority” so they don’t see it as absurd.