Concept doesn't seem to be any different than the bubble levels we all use on our scopes or scope bases to eliminate cant. I don't shoot iron sights much at longer ranges, but an anti-cant device would be no less important than on a scoped rifle.
07 FFL /Mosin-Nagant Custom Shop/Bent Bolts
Genuine Cerakote Applicator- ALL FIREARMS
General Gunsmithing and Re-Barreling, muzzle threading and brake installations