Protein is definitely important, but the maximum amount one can consume in a single sitting is hotly debated in some scientific circles. For someone working out frequently and trying to make serious muscle gains, some studies have shown them able to process up to .55g per kg, per meal, up to 4 times a day or 2.2g/kg per day. For me, at 200 lbs would be 45g four times a day, but not everyone can process that much, nor is it necessary. The World Health Organization's recommendation is .83g/kg per day, which ends up being about 25g spread across 3 meals, which they estimate would meet 97% of the world's population's protein needs.
During the healing after surgery, protein helps repair and build tissue. During rapid weight loss, along with some movement, it helps to maintain muscle mass, but you can't eat enough protein during this process to eliminate some muscle loss. Once you reach your nadir, your protein needs really depend on your goals. If you are building muscle, protein needs go up, but to maintain it, you don't need as much.
Being almost 100% vegetarian, I get right around that minimum number. My muscle mass is still above normal. Some of that is genetic, but I haven't needed to eat large amounts of it at all to maintain my muscle.
Finding a source you trust is important. I personally don't think most doctors are actually the best source of nutritional information or even dieticians in many cases. They tend to follow the the "medical industry" suggests, which is not always based on what modern research has discovered. They are often way behind, and most doctors have very little nutritional training unless they've taken a very special and concentrated interest in it.
That being said, short of finding research you trust, you should follow the advice of the people on your bariatric team. Obviously, their advice will be a safe way to go since they have provided that advice to thousands of people. It's a risk to branch out on your own, so the best advice is to stick with what your bariatric team suggests. Of course, we have free will, so experimenting is always an option, but we have to live with the results, for better or worse.