Most homeless people are either mentally ill or addicted. It's likely that the man simply couldn't help his exceedingly poor judgment in criticizing, even in jest, any motorcyclist's ride. (That's evidence of bat-crazy all by itself.)
For the biker to return fire with screaming obscenity and then to brag about his strange behavior on a pilot's forum might indicate some real significant issues
upstairs for our Cranky Old Man.
That can't be, because Cranky has at least a Class III medical, right?
Therefore, there's a rational excuse for the peculiar outburst. It must have been the first time the poor guy ever heard that not-very-original suggestion, and he must have been devastated. There, there, dear. That unfortunate Mr. Homeless really didn't mean his suggestion the way it sounded. Your bike is surely much nicer than any Harley. Pat, pat, pat.
Also, Cranky might consider two more things: First, that some of us don't care to hear the breadth and depth of his erudite vocabulary.
It makes us feel inferior, because we don't know all those big fancy words. And second, the next scruffy dude he treats to a display of his anger mismanagement might NOT be homeless, but he might have equally poor judgment, with an equally short emotional fuse, and he might, as alluded to in previous posts, be carrying.