When the issue of bariatric surgery comes up, you've crossed the line from physique enhancement to a serious medical issue. None of us here is qualified to answer. I always tell people that if I had done better in chemistry I would have gone to medical school, but sadly, that does not qualify me to give medical advice. I will say this though. While such surgeries are, in a sense, "quick fixes," some people are in such dire health straits that they need a quick fix to get their weight down.
Whether it works long-term is problematic since many people who have had bariatric surgery gain back a lot, sometimes all, of the weight they had lost. However, I would think that a good bariatric clinic will address some of the behavior modification issues to maximize long-term success. Look into getting a second opinion.
If your father's diabetes is not well controlled, he may need a rapid weight loss plan just to save his life. Since he's not complying with your diet and exercise recommendations, the surgery may be necessary in his case. These are all issues that need to be addressed. In short, don't write off the surgery as a fad without looking at your father's individual case.