I saw one proposed edit today, the comment given was:
Comment: The comments show that my upvote of this answer was misplaced, but retracting is not possible due to mass unvote prevention, so hereby unlocking for all current voters
I voted to reject the edit, as this seemed like misuse of the edit function to me. However, I can of course understand the motivation of the user.
Therefore, is this a behaviour which is forbidden, tolerated or totally okay to use?
I understand your conundrum and think that you made a wise choice by following your ethical instinct and then raising the question here on Meta. I think that it might not be wise to make one unique rule. Rather these type of edits should be ruled upon on a case-by-case fashion by weighing how harmful the edit is. The fact that these edits don't seem to be very frequent is IMHO another reason to handle them case-by-case.
In this particular instance, one would think that an edit aimed at allowing people to revert their votes shouldn't be necessary, since the community is usually very effective in up/downvoting correct/wrong content. For this reason I personally would have rejected the edit in the same way you did.
