If you have a 14 year old dog, meh. It's true that the surgery might be more than he can handle at that point.

But the dog should have been fixed years ago. Fixing dogs (both male and female) reduces overpopulation, reduces the chance of unwanted puppies, cuts down on the amount of animals killed in shelters or living on the street, reduces their urge to roam, decreases the chance that they will be hit by a car, prolongs their life by decreasing the chance of different types of cancer, and more. So in most cases, I think it's cruel not to spay/neuter.