Firstly, Commandment #8 was written when the Guads were in a state of post-rant mellowness, somewhat equivalent to the flat-lining that happens on the day after popping a pill of ecstasy and clubbing all night. Or so I am told.
So with that in mind, here's the First Amendment to the Commandments, and it applies to #8:
8/ Thou shalt not look down or differentiate between any cyclist based on frame material, choice of groupset, wheels, color, tire width or attire. Hipster skinny jeans and triathletes are bereft of this exemption and thou are free to mock them as much as ye want. In addition, Roadie Scum are hereby given license to sneer at all other cyclists for any and all reasons whatsoever, provided that their level of contempt for others shall never exceed their degree of self-loathing.
That about sums it up. Roadie Scum are allowed to be haters. After all, it is the essence of being a roadie scum.
Think about it - they shave their legs, they stick a hard saddle into their taint, they pay big $$$ for a bike whose sole purpose is to be so stiff that every little bump on the road gets transmitted via said rigid, lumpy saddle right into their taint and despite all of that, there is always someone faster. Anyone who embraces this has earned the right to sneer at others, if for no other reason than to maintain consistency.
As for why the Commandments mock Triathletes, it is very simple. I'll use a set of images which are absolutely neutral and representative.
And, as the coup de grace, compare a typical cycling event (NSFW) with a typical triathlon event (NSFW and definitely not for the squeamish).