Makes sense since excess protein is converted to glucose anyway. So ultimately, too much protein equals too much carbs, plus a bit too much of substances typical of mass farming.
i'm also unsure how much is too much, but fat does affect insulin sensitivity
the issue would be to reduce fat consumption as much as humanly possible, while taking regular blood sugar measurement, only diabetics do this and it's already late by then.
The abstract of that study doesn't mention carbs. That's a very important detail. If you're eating a "normal" amount of carbs (like in the vast majority of studies of this type, even "low" can mean 25%), it is true that saturated fat makes it worse. But in other studies it has been shown to be the opposite with a fully ketogenic diet, i.e. when the body can't make glucose from carbs or protein and resorts to fat instead. Insulin _must_ be low for ketosis to happen. Insulin is also triggered by low sodium.
I cannot find a single study showing insuline resistance due to high fat consumption when consuming <5% of calories in carbs and <25% in protein.