I think the libertarian case for Trump in 2016 was very simple: he was less of a war hawk than Hillary

In 2020 it was much murkier.

Trump was a mixed bag on liberty, probably overall negative (like all recent POTUS).

I'm not aware of any libertarian silver lining at all on Biden. Maybe he would be lighter on pot or something (supposedly pot is now being re-scheduled to be less seriously prohibited). I guess that counts, but we had a bunch of states with legal pot under Trump, so how much difference does it actually make?

As to the Department of "Justice" in particular I am skeptical how much power Trump really had. I think the bureaucrats mostly contained, routed around or flatly ignored Trump & his officials.