Under what circumstance would you even be able to suggest an edit on a deleted post? If you can view a deleted post, and is not the post author, you should have the editing ability, right?

Well, I guess if it's deleted between starting and submitting the edit.

(I know you know most of this, but I include the context for future readers).

On Codidact, abilities are not based on reputation, but instead are gained independently, which means they can be gained in a different order for different users. A user can have the Curate ability (which allows them to see deleted posts) without necessarily having the Edit Posts ability.

I acknowledge this is a rare combination, but in the rare circumstances required the suggested edit may be left stranded if the author no longer frequents the site.

I don't see how a user can meaningfully have and use the curation ability without first acquiring the editing ability. I'd call it a configuration error if that is possible.