Biden could, whenever he feels like it.

He can order any goverment agency to do pretty much anything.

If the agency head refuses, Biden can fire them.

If the next person in the chain of command refuses, Biden can fire them too. Ideally he’d be replacing them, but even if he couldn’t, he could just run down and see how many people would throw their careers away to slightly delay a rightful investigation.

I don’t think it would last long.

Hell, not a single one resigned when Biden ordered return to office. I guess this isn’t as important to Biden to put the same about of effort in here tho.