Because the hush money case is the only case that is likely to happen before the election.
The J6 case in DC got screwed by the Supreme Court refusing to take the appeal before waiting for the DC appeals court to rule. It was obvious that the Supreme Court was going to step in and rule, so Jack Smith requested them to just take the case and they declined saying they wanted to let the DC court decide first. Then they took the appeal a month or so later anyways. Now they have held hearings, but even if they rule against Trump, all they have to do is delay until late July and they know that the justice department won’t be able to resume the trial in time.
In the documents case, which is the most fundamentally simple case, Eileen Cannon has ratfucked the whole process to the point that it’s unlikely to start before July. It should be an open and shut case, but she’s entertaining all sorts of crazy legal theories and giving them months to elaborate on them.