If a user's account is scheduled for deletion (i.e. they've submitted a formal request for account deletion, but the button hasn't actually been pressed yet), can they be prevented from voting?
I can't see any reason why such a user should be allowed to continue casting votes on the site. They've already decided that they're soon going to be a non-user, and they won't be able to vote at that point anyway; and if they really want to continue voting, all they have to do is cancel the deletion.
On the other hand, there are sometimes good reasons why they shouldn't be allowed to vote in this period. In many cases (not all), a user deleting their account is in the middle of some sort of "rage quit", and an obvious thing for a ragequitting user to do would be to leave a bunch of downvotes before they go, as a form of hitting on the break. If they do it soon enough before the deletion, they might even be able to get away with doing things which would normally be reversed by the serial voting algorithm. Or, worse, they could unaccept answers to all their questions - downvotes can be invalidated by SE employees, but nobody except the OP can re-add checkmarks to answers. For that matter, even the standard ragequitter practice of deleting all their posts could count as a sort of voting - it's disabled during account suspension, so why not during pending deletion periods too?