Here I'll help.
You think:
A gay man fukking a gay man, consensually = a person fukking a dog, when in reality it is not. In an attempt to illustrate this, you came up with a scenario in which someone is forced, that is, non-consensually, at gunpoint to have sex with a man or with a dog, stating that both instances would be equally disturbing. Which, no shyt, it would be, someone is being forced with threat of violence to have sex.
Now back to the consensual gay sex = dog fukking thing. Dogs, as non-human living beings, that is, as animals, are incapable of consent. Additionally, fukking a dog would most definitely cause some sort of damage to the dog's well being or your own. Additionally, a dog is not human, don't fukk dogs, it is nothing like two humans (consensually) fukking each other.