Yes, it can be frustrating when your users don't know as much about your product as you do and ask for help in a vague way. It's unintuitive that a color named

Yes, it can be frustrating when your users don't know as much about your product as you do and ask for help in a vague way. It's unintuitive that a color named green would correspond to the color on the left that I don't think most people would think to check. It's totally fine to have a policy of not supporting OSX, as long as you communicate it with professionalism or at least civility.