I think Michael Walzer makes a strong and important case, but to be fully convincing I think the case has to be made concrete and specific: what actions does he suggest follow from his general conclusion? Should Biden pledge to pardon Trump--or not pledge but just do it? (He's said he wouldn't pardon him.) Even if Biden pardons him, Trump can still be prosecuted for NY state crimes and Biden can't pardon him for that? Perhaps Walzer would say such crimes would be less connected to his presidency and so not entail the risks he (rightly) warns of, but I'm not sure it's so easy to make that case. If Walzer thinks the Justice Dept should have a policy against prosecuting presidents for any acts while in office, I hope he'd agree that 1) they should still investigate somehow, no matter what, if they find evidence of a crime and 2) such a policy should come from Congress (though if passed as an explicit law, that would have the effect of encouraging law breaking to some extent no? and that too must be taken into account). Unless I hear more concrete details from Walzer as to how his non-prosecute proposal would be made a reality, here's where I stand: until Trump's handling of the pandemic killed people, I might've argued Biden should have pardoned Trump if he had been prosecuted for other crimes for the reasons Walzer suggests. And even despite the pandemic, I don't think Biden or Democrats in Congress should actively prosecute the case against Trump after he leaves office, for the reasons Walzer gives. But if the federal Justice department or local and state officials prosecute Trump according to their standing policies and directives, I don't think Biden or other executive officials should intervene to stop that at this point.