While velocity (fps) may be a readily enforceable standard, I personally feel the kinetic energy is a better measure for what it takes to kill an animal, esp of the size specified. IMO, while less can get it done, 100# KE is required to harvest deer humanely. I'd want at least that much for moose and significantly more for brown bear.
As for sights, I would not put any limitations on use of same. Given that any archery is a close up endeavor, a magnifying scope won't make any difference as to how far an archer can shoot. It would seem that accurate shooting is not just desirable but essential here. Most quality crossbow scopes now have multiple aim points on their reticule, whose spacing can be varied-by changing the magnification-to match the arrow's trajectory, thus they can definitely make a big difference to precise arrow placement over open sights, non-magnifying scopes or red dots or reflex sights.