My very first cancellation was a pain in the a**. And it was my $5 at that time… Not sure if it is the first cancellation for you though, but I know how you are feeling.
Anyways, you can either spend your entire free time fixing the work and risking to get another cancellation request and/or getting a very bad review.
Or, you can agree to cancel the order.
It is most likely a scam, since you offer .gif-related services, which is much bigger chance to get scammed. He might’ve just planned to do like that, to get their work for free.
You can also contact CS and tell them that he had broken TOS, wants to communicate outside Fiverr. But… I don’t think you would get a response from them any time soon, probably in over 10 days, so let’s scrap this idea.
If I were you, I wouldn’t be risking, and would better take the cancellation, get more free time, but lose a bit of money and lose order completion rate, which would reset after 60 days anyways.
It is up to you on how you want to manage this situation, but hey, I just told my opinion about it. Oh, and be sure to report the buyer, he did broke a few TOS over there!