What significance is dietary cholesterol?

It actually isn't the case that lower LDL is better. It's that the ratio of LDL to HDL should be low.

LDL goes around repairing arteries. When LDL delivers its load of fatty acids it stays in place until the HDL comes and cleans it out.

If the LDL is low then your arteries don't get repaired. But if HDL isn't high enough then the LDL hangs around, forming plaques (heart disease) and that's bad.

It's carbs that are causing a lot of the inflammation in the first place. So if you reduce carbs then less LDL needs to go to repair arteries and then less HDL is needed to clear out the LDL. Basically you should aim to have a surplus of both LDL and HDL.

So eat up the eggs and shrimp, and don't eat wheat, bread, flour, pasta, potatoes, rice, etc. :-)

It strikes me as a fairly plausable piece of pharmacological reasoning - using plant-derived man-like antagonists to block receptors and therefore stop transport of potentially harmful compounds into the body. However, I have absolutely no idea of how effective it could be. I think the receptors are mediated by far too complex a mechanism for this to be the sole factor. The pharmacokinetics and dynamics are probably variable at best. I imagine this is scientific research with a bolus of i.v. hubris at some point.. pardon my attempt at humor.