well, i don't want to be rude but that friend of you is an idiot, or he has never seen someone with a tan, and of course, your character is, i assume, fishing at the beach, so, unless your friend goes to the beach wearing gucci boots, or dressed as someone in the oscars, then he is an idiot.
No, is not racist nor colorist, it has nothing wrong with it, and i can't see a valid reason of why someone would feel offended by it, he is one of "that people" i guess.
Your art is really good by the way, do not pay attention to that kind of comments, people with no perspective, you will find a lot of those in your life, so just ignore it