I have no idea what Jeff Smisek is like as a real person. But I would imagine that he would be greatly displeased to hear this. As CEO of United Continental Holdings, he still oversees United Express. And those planes carry the United name and globe logo. He also owns an awful lot of shares in the company.
I think it's worth sending something specifically to his office. If your tone is diplomatic, I think one of the most important messages is, "This is how your name is being used in ordinary conversation with passengers." It's used in much more derogatory ways, but it should be a, "Mr. Smisek: I think there is a big problem."
He may be such an egomaniac that he doesn't care at all, and he's just happy that is name is being mentioned. I tend to lean on the generous side of things, so I'm going to suggest that he would want to take a second look. It would be a tough one to fight; he can't exactly sound out a memo that says, "Do not use my name like that." But perhaps his advisors can come up with ways to mitigate this for him.