Obama is irrelevant?   You really lost me there.   He is specifically claiming that he was fired for protesting Obama and being photographed by the media holding an "OBAMA GO HOME" sign.   

An employee or contractor's job should not depend on what politicians the person does or does not support or does or does not protest.   Should the city in a few months fire all employees and contractors who say that they voted for Donald Trump in the upcoming primary??    Should they terminate any Democrats who supported Bernie Sanders, and opposed Hillary Clinton?

If political speech is allowed to determine whether a person keeps their job or not, then just how far down the rabbit hole would this go??