The Court will rule for Trump but leave open the question of whether the congress could refuse to seat him for insurrection. The question becomes which congress? The old one or the newly elected one.
They could initially refuse to seat him but it would have to be done via state delegations not by numbers of a party in congress. If the Dems were to get the congress again by just a few members but Pubbies control more state houses then The president would be seated.