Who is competent to decide what offends?

>The following statements are included: >“You speak good English.” >“When I look at you I don’t see color.” >“America is a melting pot.” >“America is the land of opportunity.” >“Everyone can succeed in this society if they work hard enough.” How long until people start deeming the phrase "America is a country" as a cultural and racial micro-aggression? I'm happy the author calls bullshit on people trying to say "XYZ is offensive to those people!", but the author still seems to support micro-aggression training if they get "better sources" on trigger words.