He says that fructose is metabolized differently than other sugars, i.e., rather than being converted to glucose or glycogen, the liver converts it directly to fat. So, the more fructose, the higher incidence of fatty liver disease, insulin resistance, etc. While HFCS is an obvious villain, ordinary table sugar is actually pretty bad too. Commercial HFCS is about 55% fructose and 45% glucose, whereas ordinary table sugar is about 50/50. Different, but not all that drastically different.
If we're talking about a precise line in the sand, then almost certainly not. Even the reference ranges your lab uses to evaluate blood components are a little "soft"; we do the best we can. As you say, individuals vary and other factors play a role. But it certainly should be possible to determine useful ranges; stay below this range and you're mostly safe; go much above it and you're into redline territory.
Oh, and one other theme I forgot to mention: he cites chapter and verse to illustrate how, deliberately and with premeditation, the industry has worked to downplay or flatly deny that there are any real dangers at all—very much as big tobacco used to do.