The DC Circuit Court of Appeals has already shown that it is going to move very quickly on this issue. If that had not been the case, SCOTUS may have decided to take it up. As it stands, SCOTUS wants to stay out of all this as much as possible; there is no ruling they can make on anything Trump that won't result in a huge public uproar, possibly leading to violence, possibly leading to violence against the justices themselves.
SCOTUS can't rule that presidents are immune from criminal prosecution for any actions they take while holding office. Not for love of democracy, not for self-preservation, not to protect any corruption status quo. They would need to rule against Trump, and that means violence.