No, but it also isn't something that should be turned into a double standard (yet another in which the right excels). Should Sanders have been kicked out the restaurant for working for Trump? No. But neither should other people be kicked out of other places of business for being gay, or black, or Hispanic, or Muslim - all of which the right continually praises on the grounds of "religious freedom" or some other similar ideal.
Here's another thing though: any and everytime Trump says anything like this, his supporters immediately defends his words with the same stock response: "He was just joking." That, in and of itself, is another double standard: anytime Obama would make jokes, or try to invoke humor into something (his speeches, statements, addresses, whatever), those same people would slam him for being un-Presidential, inappropriate, and "trying too hard to be Mr. Cool than the President of the United States." Trump on the other hand, he makes these remarks, threats, statements, whatever, and his supporters always defend him as joking, having a sense of humor, or "telling it like it is."