It could have been water under the bridge if we simply did not re-elect him. But now we have a second term emboldened by de facto total immunity.
Responsibility for Merrick Garland's failure to adequately pursue Trump lies at Joe Biden's feet and will likely be the thing he is remembered for most in the history books* despite the fact that he had some decent domestic policy (and some horrific foreign policy).
* (assuming we work our way out of the current mess, if we don't he will be remembered for far worse things given that he's Trump's reflexive whipping boy despite the fact that it makes Trump look weak to keep droning on about Biden)