Explain exactly why that makes me a scumbag? They have a right to remove anyone, for any reason. It is their business. A shitty, horrible move, but their right as a private entity. How on earth does correctly asserting that they have that -legal- right make anyone a scumbag?
Are you concerned about the other 3 passengers who were asked to leave? I've not seen anyone point out how they were also ill treated for having to get off the plane, but because this passenger refused to, he had to be removed. I imagine the fact he is a doctor plays into this, as I imagine a hillbilly refusing to leave because "damn, I'm American!" wouldn't engender the same "Scumbag!" responses.
I mean, the fact many of the "defenders" have criticised United for the shitty move doesn't seem to register. I personally haven't been saying "Yeah! Do it, kick them off, you guys are amazing!"
It's disgusting that you're able to make sweeping generalisations about a person for pointing out that a company did a shitty thing, that by all legal means, they had the right to. Should they have done it? Probably not, but that isn't the point.