I think the idea of giving a warning is stupid. On the other hand the idea of political correctness just used to be considered being polite and having manners. People should know their audience and know a person well enough to decide if this is a conversation you should be having in the environment you are in. The constitution protects you from government intrusion into your free speech. It doesn't prevent one person from telling another how they feel about their opinion. Most people who hate "political correctness" otherwise known as "being considerate of others", just want to be able to tell everyone what they think but don't actually want to hear what others think about the given subject and when they get push back, cry about their free speech being violated.