Shouldn't employers abstain from controversial subjects as well, then? It seems one sided to hold employees to that standard but not the corporations and bosses they work for.
Every day the "pro-diversity" (in the sense of preferentially hiring practices) don't abstain... they tell you a viewpoint and force you to adopt it even when you disagree. The fact people keep their mouth shuts shouldn't be a surprise. That doesn't make the pro crowd any less controversial. It's just they don't get fired for their controversial opinions.