Which also means that some insulin spikes aren't even necessarily detrimental, even for a Type II diabetic.
Not always, but they can be detrimental. Many people, not necessarily you, confuse a rapid increase in insulin with a rapid increase in glucose. They are different. In the study I linked, Whey protein didn't increase blood glucose. Why? Because it increased insulin instead, and insulin kept the blood glucose down.
In some people, when they first start developing insulin resistance, their fasting blood glucose appears normal and they and their doctor will think that everything is just fine. However, after testing their fasting insulin, it's very high. Their body is having to release more and more insulin to keep their glucose levels normal. This is bad. Most doctors test fasting blood glucose, but they won't test fasting insulin unless you request it, and possibly pay for it out of pocket.
If not treated, this person's glucose levels will eventually go up as well because the high insulin will no longer be able to keep their glucose levels normal.
So insulin and glucose levels are two different things that must be looked at in relation to each other.
Also, increases in insulin from dietary protein are far lower and more stable than they are from dietary carbs:
There are of course many who say you should avoid protein induced spikes too,
And you definitely do if, for example, you are on a ketogenic diet to treat epilepsy. Eating one too many ounces of protein could trigger a seizure.
and in fact a "true" ketogenic diet is just mostly fat and low carbs.
Where do you get this from? The ketogenic diet for epilepsy is less than 5% carbs, 80%-90% fat, and the rest is protein. A ketogenic diet to treat type 2 diabetes is around 70% fat, 25% or more protein, and 5% or less carbs.
A "bodybuilding keto" diet isn't really even ketogenic due to the massive gluconeogenesis from amino acids (aminos turn to glucose) That's why some have been able to eat a zero carb diet AND use insulin at the same time, due to proteins like whey in massive amounts.
What's bodybuilding keto? A keto diet is one that gets you in a state of at least mild ketosis, at least most of the day. How much protein one can consume while staying in ketosis differs by individual.
Many people believe that gluconeogenesis uses ONLY amino acids(protein) to create glucose. This is incorrect. It uses lactate and glycerol(fat) too. Ketones are muscle sparing too, as fat adapted muscles use mostly ketones and fat for energy and require less glucose/glycogen, thereby decreasing the need for gluconeogenesis.
Insulin is a hormone, not a source of energy. Did you mean to say glucose?
I haven't delved into it that deep but some can have relatively poor insulin sensitivity on a ketogenic diet too. It's not that simple 
Where did you hear/read this? That would be true only if those individuals already had poor insulin sensitivity and had just started the keto diet recently. Study after study have already shown that a well formulated keto diet improves insulin sensitivity.
Genetics are huge wrt insulin sensitivity/resistance. I read that for example a Nordic person may be able to gain 30lbs of pure fat and not go Type II diabetic whereas some indian in south America can gain 2lbs of fat and go diabetic.
This is true, but genetics load the gun and environment/lifestyle pulls the trigger. You can improve and maintain good insulin sensitivity through lifestyle, no matter your genetics.
