I'd rather not add that back in, because it seems like it would just be an inelegant hack to let you do what you want. So what exactly do you want? Maybe it can be incorporated in a more useful way.
If you want to exclude certain battles (like a person goes afk) then is the Pause feature sufficient? If this is something you want to do after the fact and you want to make multiple files to edit out certain fights and view the results in different ways, then I'm not sure. Ideally it could be incorporated into the UI where it has a list of every fight and you could just click something that says "Exclude this fight", and it would recalculate the results.
As a workaround in the interim, do you have access to any tools that would let you view the database?