I am proposing that in some circumstances a rejected migration should not be automatically deleted from the destination site.
In the case where all of the following are true:
- The question has a score of 0 or higher, counting only votes cast on the destination site, and
- The question received at least one answer, and
- At least one answer has a score of 0 or higher, and
- An answer was accepted, and
- The question was closed more than 14 days after it was answered
then the migrated Q&A may have some value and should not be automatically deleted from the destination site.
This describes an edge case for which an example is available. While this took place on Server Fault, I believe it is applicable to all Stack Exchange sites.
It may be wise to add additional restrictions to this. For instance, in this example case the question was answered and accepted almost immediately, but was closed a full month after its migration.
It may also be wise to tweak the requirements a bit, for instance by requiring an answer to have a vote count of 1 or higher.
My primary concern here is that, when a question posted on a site is closed, it may still be reopened later. If the question has not been downvoted and has an accepted answer, it almost certainly has enough value to not be deleted. However, migrated questions which are rejected are treated much more harshly, even though the value of the content is the same as if it were posted to the destination site in the first place. We are losing some value by automatically deleting some of these questions.