The proponents did defend it in federal court. They lost.
It's true that the Supreme Court wasn't interesting in hearing from them again, but there is absolutely nothing to suggest that if they had, it would have turned out as anything different than their disastrous showing in federal court. Remember, they were going to the Supreme Court seeking appeal, which means they don't get to re-litigate the whole thing, just to raise questions about particular points of law. The findings of fact would stand, and as far as facts went, they had nothing.
It's true that the Supreme Court wasn't interesting in hearing from them again, but there is absolutely nothing to suggest that if they had, it would have turned out as anything different than their disastrous showing in federal court. Remember, they were going to the Supreme Court seeking appeal, which means they don't get to re-litigate the whole thing, just to raise questions about particular points of law. The findings of fact would stand, and as far as facts went, they had nothing.