As a straight white male working for a former startup: I agree wholeheartedly. Even when (maybe that should be especially when) you are supposedly encouraged by the company to do so.

Discussing politics, race, sexuality, or religion at work only ever leads to discomfort or hurt feelings on someone's part, even if they are superficially identical to you.

Hell, even someone being vehemently anti-Trump at work makes me super uncomfortable, even when I feel similarly.