From your pooch's point of view, he really doesn't need to be groomed. Oh, and that brush makes him very nervous. In his mind, he is probably thinking something like, "Hey dad wouldn't you rather be outside going for a walk or playing?" It will take some time to train him to be calm enough for you to groom him.
Although Buddy might have a short coat that you might think doesn't need much in the way of grooming, this is not the case. You should groom your pooch once a week, whether he looks like he needs it or not. This is good for his health and a great way to bond with him.