I think we need to understand how sponsorship/branding works to really understand what's going on here. Not forum blasting you here btw. I work in advertising, so I do this for a living.
In this hypothetical scenario, it's not that Ford "supports" the KKK directly by having an ad run before their video. It's because human emotion and long term memory are handled by the same part of the brain, and as a result, they trigger each other. Anyone watching a negative, hate-filled video of any kind is going to associate negativity and hate with the Ford brand name. And once branded, when they feel negative or hate filled, they'll think of Ford. And when they think Ford, they suddenly feel negative and full of hate. It works the other way, too. Your local gym hosts a "Run for Cancer" charity event in the neighborhood. It's a good thing, people come out and support it. Tons of businesses help sponsor this event. People will go to this event, feel good for participating, and see the sponsor's logos. Feel good, see logo; see logo, feel good. See logo, feel good. You get the picture, and that's exactly what sponsors are striving for.
As a result, big brand names are leaving YouTube left and right for this very reason. They simply can't control who their logo shows up next to, and it hurts their overall image.