Marit Kolby Zinöcker may have figured out why. "Most cholesterol is distributed throughout our cells. Cholesterol is an indispensable part of the cell membrane"
When we eat more polyunsaturated fat, the cells incorporate more polyunsaturated fat into the cell membrane, making it more fluid. To compensate, the cell also incorporates more cholesterol in the membrane. Cholesterol has a stabilizing effect on the soft membrane.
If we eat more saturated fat, the opposite happens. The cell membrane becomes stiffer and no longer needs that much cholesterol.
So there's a natural, benign, and indirect connection between fat in the diet and cholesterol in the blood. If that regulatory connection goes haywire you could have problems. One way this might happen is a known risk factor for heart disease--chronic inflammation.
Or maybe we can overwhelm the regulation the way we can overwhelm our insulin system; she's not claiming to have the solution yet. One obvious question is: "Is the distribution of the rate of LDL in the blood for a given amount of dietary saturated fat the same in healthy people as in people with risk factors for heart disease?"