I know it was filed and rejected. The USSC almost always takes cases when there is a dispute among the Circuits. There was no dispute in this case, since this is the first case with a ruling on vaccine mandates.
Now the USSC will most likely take the case if the same issue comes up in another Circuit with a contrary finding i.e., rejects vaccine mandates.
The USSC would be obliged to hear the case because the issue would then be in dispute and the Court wants a consistent rule of law in all Circuits.