Actually, you raise a good question, facetious or not. I have not yet seen the entire opinion published online. But, it will be interesting to see if the opinion carves out any residency requirements for the illegals. If it doesn't, I'm not sure how they could deny your posited scenario.
"The lawsuit contended the California law usurped a federal prohibition on giving educational benefits based on residency to illegal immigrants but not all U.S. citizens."
But note the court's amazing sophistry. Instead of "residency" requirements, they have the requirement of attending Cal. high schools instead.