I agree that someone with a Youtube channel can say whatever the fuck they want. I also agree that if viewers want to then consider the guy to be a chode afterward and unsubscribe from his channel, that's all fine and great, too. If you watch Youtube, you risk running into someone who is going to spew horrendous bullshit that you don't agree with. If you have a Youtube channel and spew horrendous bullshit, you run the risk of watching your subscriber count spiral down the toilet (though a few of the turds that were already in the toilet might splash back out and increase your subscriber numbers by a bit, because they are the audience that enjoys such horrendous bullshit).
That said, I'm really rather ambivalent about the whole "unsubscribe/unfollow because someone has incredibly shitty opinions about politics" thing, myself.