Earlier quoted context omitted.
> I'd be slightly more confident (slightly) that editing the post might cause the core data in the db to be updated I'd be much less confident, considering that they explicitly save and make public post's edit history.
This is the case with many other online platforms (such as reddit) in that the original content of a post is still reachable if it was deleted, so a common method is to "scrub" edit your posts then delete them. However at Facebook's size, and given they're known for 0 privacy, they likely track all changes anyway.
I don't think editing a Facebook post first would have the desired effect.