Hi there, Dennis.
I had a quick check via Google and cam up with
this. if you have a good read you will see that the surgery is not that nice and the urologist is probably thinking that if the diverticulae are the result of obstruction of the bladder outlet (guessed from the prostate surgery) then things may still settle down and no action be needed. Surgeons try and avoid surgery if at all possible and especially open abdominal surgery that your diverticulae may well need.
Really, you need to have had a good discussion with the surgeon so that you understand what the disadvantages as well as advantages of the surgery are and the reason he thinks surgery is not needed at this time. of course he may also be concerned at the effect of anaesthesia on you - the risks get more as we get older.