Summarily invalidating all votes from a user who has asked for their account to be removed is both incredibly disruptive and unnecessary. If a user asks to be removed from the site, they shouldn't be allowed to take all of their votes with them.
Yes, even if they've engaged in voting fraud. Here's why: any votes that were invalidated during their tenure on the site don't count anyway.
Don't throw away all votes when a user is deleted is not a duplicate. That post refers to user accounts that are deleted by a moderator.