Dave, my opinion has always been that IAM & AFA let things stand without appealing to the SCOTUS because they recognized their chances of being heard, much less being able to win on appeal.
Only 1% of all cases filed with SCOTUS wind up being heard, which ultimately leaves the lower court ruling to stand for the other 99% of appeals filed. When you consider that the 9th Circuit accounts for 20% of the population, and 33% of the cases heard by SCOTUS, that reduces the chances even more for a labor case being heard.
I know you probably believe that nothing risked is nothing gained, but the end result would have likely been the same --- the lower court's ruling would be upheld -- and that would have then created an even more undeniable fact of case law. At least now, there's the opportunity to take it to the higher court in the future.