Of course, being the lazy guy that I can be, I do wonder now whether we should simply ignore the existence of backroutes that use glitches, instead just pretending that the game does bar those glitches. A0;(Although, I'd probably still hack the game to at least fix the inconsistency regarding miners facing left/right and one-way walls.)
Of course, it depends on how much work the hack would involve, which I know nothing about.
I'm a bit worried about how this would affect some of my other levels, in particular "Lemming Dilemma" (not that I know whether you're planning to remake that one at any stage). For that level, it's required that the digger can survive the fall from the thin platform on the left after digging it, but a faller can't. Though I guess you can simply make the platform a little thicker if necessary.
If you are sure that level will still be workable, I have no problem with the suggested change.