Although you can never tell for sure what a jury would rule, I do believe that the man was justified in his use of force in this situation. To see why this is, consider the following quote from the link below:
Generally a person may use reasonable force when it appears reasonably necessary to prevent an impending injury.
So, did the man in his home have a reasonable cause to believe that he was going to suffer an impending injury? It seems to me that he does. He is 62 years old. There are two men walking towards him who are in his house illegally. It seems perfectly reasonable to believe that the two men are going to injure him.
Was the force reasonable? It seems to me that it was. The man was never going to be able to defeat the two intruders with less than lethal force. Therefore, the amount of force used was reasonable.