His motives may have been in the wrong, but his friend was spitting some pretty good nuggets of wisdom there. Ignorance may not be an excuse, but the only way that a person can learn to get past that is to either learn from experience (which can be problematic if you aren't even aware that what you're doing is wrong,) or by having other teach and guide you. It's also important to note that it's not enough to tell someone to just not do something because the why is also pretty important, especially if you see other people doing it. Like the Peace symbol example, if you don't know what it means in Greece, would you really of avoid using it if someone just simply told "don't make a peace symbol while your traveling through Greece," especially if it's say, a trademark you use on social media when posing for pictures?