Perhaps the supervisor overreacted -- though I kind of agree with Joe that if a supervisor thinks something you're wearing on the job is inappropriate, most often you need to go along with their request to change your attire, and if you don't you're being insubordinate, which is grounds for being sent home.

Still, I can see the "slippery slope" rationale here.   Should a political candidate or party have to allow their employees to blatantly broadcast their opposition while working at one of their rallies? I think it's reasonable to expect people who are on your payroll not to be flaunting their non-support of you while on the job.

And an employee being sent home, with pay, doesn't come close to comparing with non-employee rally attendees being removed from G W Bush rallies or even handcuffed and arrested for merely wearing shirts or buttons that said "Support Our Troops: End the War" or "Peace" or the like.   And those things did happen.

Heck, the Republican US Senatorial candidate in Alaska just had a news reporter handcuffed and detained for over 30 minutes just for trying to ask him some questions at a rally.