They do not want the USSC to hear it or they cannot try to last minute remove him from the real ballot and then claim there is no time to put him back on...
More importantly is that dem States will send dem electors even if Trump wins the State, SCOTUS will punt and say that States can send whatever electors they want.
The problem with this is since Trump is back on the ballot, but if the Supreme court rules in the states favor, any vote for Trump will be null and void. How that will work out after the primary or during the primary will be interesting. Everyone is assuming the USSC will rule in Trump’s favor. I know that is the right thing to do but who knows how Roberts will rule?