What is the difference between knowledge and opinion? Are the points in the sequences true or not?

Some proportion of them (between 0 and 100%) are true, others are false or neither. Not being omniscient, I can't tell you which ones are which; I can only tell you which ones I believe are likely to be true with some probability. The proportion of those is far smaller than 100%, IMO.

Read map and territory, and understand the way of Bayes.

See, it's exactly this kind of ponderous verbiage that leads to the necessity for rot13-ing certain words.

...without getting bogged down by having to explain that there's no qualitative difference between opinion and fact.

I believe that there is a significant difference between opinion and fact, though arguably not a qualitative one. For example, "rocks tend to fall down" is a fact, but "the Singularity is imminent" is an opinion -- in my opinion -- and so is "we should kick out anyone who hadn't read the entirety of the Sequences".

Identifying a problem and identifying myself among people who don't want a particular type of solution (relaxing LW's phygish standards), doesn't mean I support any particular straw-solution.

When you said "we should make LW more exclusive", what did you mean, then ?

In any case, I do have a solution for you: why don't you just code up a Greasemonkey scriptlet (or something similar) to hide the comments of anyone with less than, say, 5000 karma ? This way you can browse the site in peace, without getting distracted by our pedestrian mutterings. Better yet, you could have your scriptlet simply blacklist everyone by default, except for certain specific usernames whom you personally approve of. Then you can create your own "phyg" and make it as exclusive as you want.