Not to mention that RTs are trivially reversible: You can undo them in the UI, and all tweets can be deleted.
Surely after a few hours it doesn't really matter if the retweet is removed. Sure, it won't appear on their history but the recent timeline is the biggest use case.
Perhaps send the code after say 15-30 mins, or base the time on their follower count.
Edit: Does this violate any Apple or Twitter ToS? I've a feeling Apple won't like this, but they probably won't care.