PT, I think it's generally true that dietary cholesterol from sources like egg yolk (not oxidized, not rancid, not overheated, not processed) will not, as a standalone, affect blood levels in a way that should cause concern. This is a VERY general statement - because other risk factors, dietary and bodily weaknesses, and genetic heritage can play a role in how the body reacts to a myriad of circumstances that could affect cholesterol levels. There ARE "hyper-responders" to dietary cholesterol. For this reason, cholesterol levels (to me) are not irrelevant, but mis-interpreted and ill-used in the medical profession. And it breaks my heart when someone throws away that nutritious, delicious yolk! Especially since egg whites are far more likely to irritate the gut.
Caveat: supermarket eggs are high in PUFA. More below. Find pastured eggs and ditch the omega-3 eggs.
IF an individual has high serum cholesterol, it's much more valid to assume that the body has called on cholesterol to heal and protect itself from rancid fats and the affects of a diet high in processed foods. (Are you having a cinnamon roll with those eggs? Wink, wink)
Chris Kresser has put together an incredible page full of cholesterol-related resources, and cholesterol-and-health.com is also a wealth of information. You will undoubtedly find what you're looking for:
Weston A. Price is my favorite source for "myths and truths about cholesterol."
I think what people often blame on egg yolks, etc. is usually a result of OTHER dietary factors present. Cholesterol is a healing substance, and when blood vessels experience weakness or damage, cholesterol rushes in to repair. There are so many interactive factors here, however, that I think it would be best for you to peruse these resources so you can formulate an answer that's most appropriate for your dad.