I am not surprised some one with your limited skill set sees nothing wrong with maximizing a photo op by switching rifles and pretending one used a less capable rifle.
Possibly others view this as dishonest because bolt actions with high power variables and bipods are a bit of an advantage compared to iron sighted lever guns.
It's a great bull, why lie?
It's not your bull, why do you care so deeply?
Earlier you criticized him for shooting a bull 15 yards from the road, do you really think he'd need a scoped rifle on a bipod to do that?
Or a better question, do you really think it's any of your business what he shot it with? Ask yourself why you're so concerned with other people's business.