Earlier quoted context omitted.
That's not really what he said. He said that a Trump victory makes some people fearful, and he wants a workplace that fosters the opposite of that, and that if you cannot foster an inclusive and diverse workplace that you are not welcome. I don't think what he did say was quite eloquent and it was clearly emotionally heated, but it didn't imply nor state that Trump voters are unwelcome.
What he said: http://media.grubhub.com/media/press-releases/press-release-... He very explicitly says that any employee that disagrees with his statement should resign and the "statement" included his political views. Will wearing a t-shirt with "I heart America" get you fired at GrubHub? It's on Matt's list of no-nos: nationalist.
Nationalism and expressing love or pride in one's country (patriotism) are two different things, I think. They can be felt simultaneously but can also be expressed separately. Nationalism focusses more on cultural background, language, and heritage, which "I ︎I don't know how all of this will shake out at GrubHub. The most I've heard of the company has been around this incident. There's a lot of close and sometimes purposefully uncharitable parsing of language and cherry-picking going around in general.