Bike snobbery and road rage

then why do the majority of people that use that word fixate upon what the rider is wearing, what kind of bike they're riding or how fit they are?

you're right, the sort of behavior described is lamentable, however there's a perfectly serviceable word to describe those that exhibit it that doesn't rely on ad hominem to back it up.

I always saw the focus on what they wear (which invariably mentions fluoro) as pointing up the fundamental irony of buying 'safety gear' and then riding like a sociopath