Forget about age, this man still has it. I was impressed with how he made that shot yesterday. He proved why he is considered one of the greats of Golf yet again. I think he could compete with those who are half his age and still be able to show them a thing or two such as just becasue we're old it doesn't mean we still don't have the skills to get the job done.
Jack Nicklaus has recently shown that he still has the skills necessary to play at a professional level, but it goes beyond technical skills. To play at the professional level, one must have a great deal of confidence and knowledge of the sport and it's competitors. Jack Nicklaus has shown time and again to be one of this generations greatest golfers, and I have no doubt he would still be a top pro golfer today.
Jack Nicklaus who still plays randomly, and will do the masters could excel in the Senior PGA. He still has everything that he needs, the only issue is that he might not want to. He is not in the shape he could be, but if he were to go and do what he needed to do, to be in golf shape, he could still be an excellent golfer. He has natural ability and that can outweigh many things.
While golf isn't the most strenuous of the sports it definitely requires a large amount of dexterity and finesse. Nicklaus can try as hard as he want but, realistically, the effects of advanced age will counter most of his efforts, leaving him out of ability to compete in the Senior PGA.