The mayor hasn't said he'll fire or lay off someone who doesn't buy American. Yet when asked if he would, he has said things like "they are at-will employees in a strong mayor form of government... and they can be terminated at any time. I believe they know that and with that in mind I strongly urge that they buy American."
Of course, at least one person has come out and rung the constitutional bell, saying "It comes down to liberty... I don't see how they can tell you how to spend your money." However, Fouts says he has had no complaints so far.