Augustus' own link (MDA) says this:
The story as commonly told is, roughly, that unsaturated fat-rich LDL are inherently unstable and prone to oxidative damage, so eating a lot of unsaturated fats will mean vulnerable LDL and eating lots of saturated fats will mean stable LDL. Since the primary fat in olive oil is the unsaturated monounsaturated oleic acid, the common idea is that eating too much olive oil will make LDL vulnerable to oxidation like the other unsaturated fats.
this is exactly what brute is saying about PUFAs (polyunsaturated fatty acids).
olive oil is LOW in PUFA, as per the wikipedia link brute posted above.
brute never said anything against olive oil. in fact, brute is fond of it. Augustus is the one who confused olive oil with an oil high in PUFAs (generally these are the seed oils like grapeseed oil, soybean oil, canola oil).
basically, most MUFAs and SFAs are fine even in large quantities. they occur in nature: MUFAs are abundant in naturally fatty plants like avocado and olives, SFAs in animal fats and a few plants like coconuts. the human metabolism is pretty well adapted to them. PUFAs from pressed seeds/grains are a relatively recent invention, and the human body is not well-adapted to them. they started coming around after the fat scare, in the 50s and onwards.
trans fats are PUFAs that are chemically altered to make them more stable, like SFAs. (PUFAs are always liquid, SFAs can be solid, like butter and coconut oil). thus in order to make margarine and the like, humans tried to chemically alter PUFAs, creating trans fats. trans fats are just the worst.
it's probably more useful not to think purely in the categories of PUFA, MUFA, or SFA. fish oil contains good PUFAs, like omega 3 and 6, and a certain amount is necessary. pressed seed oils, on the other hand, are also PUFAs - but they're bad in high quantities, i.e. when used as a staple instead of SFAs from animal fat.
since Augustus brings up Mark's Daily Apple, here's Mark on PUFAs: