Is wearing a "Don't Tread on Me" cap to work a form of racial harassment?

According to the Equal Employment Opportunity Commission, it could be, even though the EEOC acknowledges that the Gadsden Flag "originated in the Revolutionary War in a non-racial context," and has been "used to express various non-racial sentiments." Such as support of the Tea Party and the Second Amendment to the U.S. Constitution. You know. Conservative stuff.

So, why is it racial harassment? Apparently because white supremacists used it once in 2014 in connection with the murder of two Las Vegas police officers (both of whom were white), and African-American firefighters in New Haven, Connecticut, believed (in 2014) that it was racially insensitive.

Therefore, the EEOC, in a racial harassment case brought against the U.S. Postal Service, decided that the harassment claim -- where the only "harassment" alleged was the co-worker's continuing to wear a "Don't Tread on Me" cap to work despite the complainant's requests that he not -- should be investigated. (The EEOC did not find that the harassment actually occurred, only that the allegation was worthy of investigation.)

Although this case involved the Postal Service, Eugene Volokh of The Volokh Conspiracy believes that the EEOC's position has a chilling effect on private sector employers (who will over-police their employees' freedom of speech and expression to avoid incurring liability), which indirectly results in suppression of the employees' free speech rights.

I don't know whether a court would accept Mr. Volokh's theory, but I agree that there are serious concerns about creating harassment liability based solely on an employee's (apparently unjustified) subjective opinion that a co-worker's expression or political opinions create a hostile work environment. Is this really a slope that we want to start slipping down?