Yeah that makes sense about it carrying some risk. I have been a product manager for a video game studio before, managed several titles, and I am still in the software development field; so I feel that feature-risk all too real.
In the quite-often use case where there is a single, simple dialog option remaining to end a conversation, like "Close Communication" (or "Close connection"... I don't recall which, but I see one of those pretty often), I'd imagine it's pretty low risk to implement a mapping of the "Esc" key to simply act the same as the "1" key, to select that remaining option. I'd be happy with that.
In the less-often case where there is a multi-choice ending to a dialog, I can see why there's higher risk involved... so I wouldn't be upset if the Escape option didn't work in those cases. Same for mid-dialog use of Esc... makes sense to me why it would pose high risk to have it there.
I got yer code right here:
If ( isFinalDialogChoice && $numOptionsRemaining == 1 ) then MapKey ( "Esc" ; "1" )