Basically Mueller was saying they can't indite him until hes out of office.

They collected and wrote notes of fake evidence so that one day they can go back and review it,

Their legal notes that were written are for a future date, and are meant to falsely charge our POTUS at a future date.

The notes were designed to show their state of mind, and that their legal notes take more presidence than evidence.

It looks like to me they're trying to engage another level of controversy by leveraging POTUS. They are attempting to keep him in line, so they can threaten him, his kids, and harass him with more legal threats after his presidency.