Well, I admit it, now it's really weird.
Can't feel the whole argument at all, sorry.
I'd understand if it was for the violence itself, some people are more sensitive when realistic blood and violence are depicted in a game, but -you know- you are talking about an horror game, so... I think that these guys already aren't interested.
But because of the digital avatar of what you are shooting at? that's new to me.
I'm really sorry for those who can't enjoy fiction that they like (violence, blood, mass murdering, torture, screams, fear) just because instead of killing a igital model of a human/bear/gragon/zombie/lion/etc is a dog. Maybe there some sort of trauma under the surface, so I think that it would be very hard to overcome.
Just skip the game I guess, but I don't see the need for a story about that. We don't have disclaimer for everything you can kill or destroy in games where you are supposed to kill and destroy things.