Rhodes did his crimes in writing, making his criminal intent clear as day. Trump didn’t put his crimes in writing, and none of the people who are likely able to testify to his participation in the criminal conspiracies have flipped (so far as we know). Meanwhile, the MAL search warrant is unmistakable proof that DOJ does not consider Trump to be above the law, and at least two additional J6 rioters have been found guilty of major felonies already today. Every indication is that things are proceeding apace.
ETA: I think DOJ already has enough to charge Trump with conspiracy to obstruct, maybe even seditious conspiracy, and obtain conviction. They certainly have enough to charge him with conspiracy to defraud on the fake electors gambit. But they’re wise to keep working the investigation until it’s factually bulletproof, because otherwise they’re taking a great risk that SCOTUS will set him free.