Ask HN: client terminated contract, should I remove unpaid-for commits?

Hey HN, wondering your freelancing two cents. I signed a client's contract which basically said "We provide work orders (PivotalTracker sprints), you code. If you finish, we pay; if not, we don't pay." Fair enough. Hacked a few work orders, got paid. Finally there was one work order with a grizzly ticket well beyond the week's allocated hours. I suggested we break it up, or ice-box it. The client said no and insisted it be completed before they accept the work order. I chugged and chugged on this one ticket, until finally (as per the work order's due date) the contract was terminated.

Now, they have all my commits for that work order leading up to the final ticket (about $700 of my time). A lot of work down the drain. My question is, seeing as the whole shebang is either accepted or rejected (not individual tickets), should I remove all my commits for that work order, since I'm not being paid for them? A simple `git rebase -i ... git push --force` would do. I'm sure someone has a local clone and could figure it out (after some cursing). Possibly enough to leverage a payout on my work, otherwise (since that's been addressed in the contract) they'll just deal with the lost work order as I am.

I don't mean to be malicious, I'm not trying to haxor their bases; I just don't want them to have my work for free. I've looked through the contract and there's nothing addressing redacted IP on failed work orders as far as I can tell. Thoughts? More trouble than it's worth?