they never have. They've ruled against him or declined review in all of his and his allies' election cases so far. The majority is conservative - in some cases almost ridiculously so (Thomas and Alito are almost off the charts), but they aren't really Trumpers. Their conservatism leans toward protection of business interests and religion, mixed with a bit of libertarianism, and with a disregard of individual liberties to the extent those conflict with business interests and religion - but conservatism and Trumpism are not the same. I could see Thomas and Alito trying to give TFG a break because they're nuts and would rather see a berserker like him in the White House because money, but the others might recognize that in the long run he's bad for business. The corporate interests hate chaos and uncertainly, which TFG produces in abundance, and they also would hate having a president do to them what DeSantis tried to do to Disney, which is bigfoot them if they don't do what he wants.
The justices don't owe him anything because they are appointed for life, and in a normal world they wouldn't have to consider political retribution for an adverse decision. But they might consider the possibility that in a second term TFG would go full-on dictator and try in some way to control or even eliminate them. Maybe they wouldn't want to risk that possibility, and would conclude that by upholding the Colorado case and allowing his fat orange ass to be kicked off ballots in any states that decide to do it, they might be saving their own hides. And they could do it by hiding behind their own philosophy of originalism.