I do not know the background on this, I am surprised this is going to the SCOTUS, that strikes me odd. Is that true?
If this has to do with car Plates on autos, this is a State decision and not Federal nor in my opinion a Supreme Court question regarding constitution et all but only State court(s) since it is each State that determines the state license and plate release.
I think this is the same "issue" that came up (briefly) on a "right-wing" radio show discussed but sort of dismissed as pretty much a non-starter. The gist was, no the State cannot be FORCED to provide car plates (in this case in Texas per the show) with flags on it of a non-US nation such as the Confederacy. Now if the STATE ITSELF uses the old Confederate Flag in their STATE flag then the state flag is fine, but no one has a "constitutional right of free speech" to force a state to have a Confederate Flag on it, a car plate is not a constitutional right nor a free speech question. If citizens don't want these things, they can talk to their State reps and stop them, actually many of these custom plates were looking for trouble and "probably never should have been allowed in the first place, they started off as money making schemes by high tax states with environmental plates and then got out of control" as the host said.
Vets and purple heart medal soldiers should have a special veteran plates and in my opinion should be free for life. If some states want to allow illegal aliens to drive cars, which is a state decision, in my opinion these plates should be flagged with an "A" for alien. And child molesters should have their plates flagged with "X".
In California, I have a "personal plate" with the name of a Hindu God. But - I do not think I have a "constitutional right" to have this plate in the name "of free speech ". The plate does not belong to me, it belongs to the State of California and it is a privilege not a right. Maybe this should not have been started in the first place, but tax and spenders in government are always wanting to grab more money or sell something - the next thing you know they may REQUIRE a "personal plate".
I didn't like either choice since I do not like the idea of "hate speech" but since this plate is NOT a free speech issue I voted the second, not because it is "hate speech" but because it isn't a constitutional question nor a free speech question.