I might suggest implementing a similar limit seen with undoing and redoing upvotes with accepting answers.
The Complete Rate-Limiting Guide says the following about accepting answers:
- All must wait 15 minutes after asking to accept any answer
- All must wait 48 hours after asking to accept own answer
This says nothing about flicking the acceptance on and off like the asker is talking about for upvotes. I think a similar limit needs to be implemented for accepting answers to prevent abuse like this.
Even with the 30 undo and redo limit for votes, this still allows some abuse like this, since it's pretty easy to count off 25 or so undo/redos and not hit the 30 limit. If you had to wait 15 seconds or so to undo or redo a vote or accepted answer, it would completely prevent this sort of rapid-fire on-and-off abuse of the system.