In their present state, they are legal C&R rifles. Once you start modding them, then they are no longer under C&R protection and the "evil" features could be (in theory) used to show you have violated import restrictions ('89 import ban) by creating a rifle not legal for import. The C&R protection trumps the 89 import ban until you start modding the rifle. In theory, once you start modding the rifle, you have to eliminate all of the evil features (night sights, grenade launcher, bayonet and mount, etc.). It is definitely a legal gray area.
This does conflict with the "CA-legal" yugo sks where they replace the grenade launcher with a muzzle brake (unsure if it is a permanent install or not). I would presume this is somehow a legal mod.
that's the background even if it doesn't make common sense.