Except that this isn't a bug. The user asked for the content to be deleted. For it to become public, they must have used a "delete" flag or something similar. The point is they didn't actually delete the content, rather just flag it as deleted.
The fact is, when Facebook gives you the option to "delete" something there is a reasonable expectation that by doing so that post, picture, etc... will be deleted. Removed. Gone. Permanently. If they want to give you the option to retrieve it later in case you accidentally delete something then call it "Flag for deletion" instead.
To do ANYTHING else is disingenuous at best. Otherwise known as a lie.
This is yet more proof that users of Facebook are the product and will be treated as such. Whoever pays Facebook actual money gets to dictate the terms and they are the people that want Facebook to never delete your data.