Is this a bug, or was this still somehow intended behavior?
It sounds like intended behavior. From Reject or approve suggested edits on deleted post?:
Our reviewing FAQ on handling suggested edits outlines why you would approve or reject a suggested edit and, you may notice, that it makes no mention of deleted posts - because it just isn't a consideration treat them the same.
There's another MSE post on the topic, which isn't Answered by staff: What happens to a pending suggested edit when a post is deleted? which says, in part:
It sits in the queue for the next reviewer