Not everyone has the luxury of the free time and effort to pay enough attention, and those people vote. I'm not suggesting absolving them of their individual responsibility. They contributed and they have to reckon with that. I'm suggesting that we recognise the role that the system they exist in plays, too. And that they're human which means they have all the failings that come along with that.
Do we hold Oppenheimer responsible for all the deaths the Manhatten Project caused? I argue we shouldn't, but he still had to personally reckon with the moral weight of it.
Two things can both be true: someone can have been part of the cause of injustice and join the fight for justice. We can both hold them accountable; and encourage their growth, offer them grace, and welcome them to the right side of history. We don't have to forgive, but mocking (at first) doesn't help IMO.
(As I've said elsewhere, no reservations about mocking the unrepentant)