Yeah, a solved thread with zero replies. Right. 
… unless you come up with the option while drafting the query and post that along with the question.
Ding Ding Ding! Fries are Done!
Being that in normal circumstances, a file will not end up on the Right side without any tags… but since saving against the naming script still applies to the left using what data is present in the tags…
If there are no tags and the original filename is not being saved otherwise…
I think I might have answered my own question while writing this out.
Check during saving, if there is no tag for a title, place substitute the filename.
e.g.: $if(%title%,,$set(%title%,%_filename%))
…and I may have found a solution for my other thread too.