A question that is migrated to another site is rejected by that site if:
- it gets deleted
- it's closed as Not Constructive, NARQ, Too Localized, or generic Off-Topic
When a question is rejected:
- it's unlocked (but not reopened) on the source site
- any answers that were deleted as part of the migration are undeleted on the source site
- all migrated answers are deleted on the destination site
- the migrated question and any answers received on the destination site are locked on the destination site
I can't find a definitive reference, but there are a few mentions of rejected migrations being deleted on the site they had been migrated to. (After 30 days?)