Service cuts and fare hikes aside, why is it that so often a Muni bus ride feels like a river cruise on the Styx with Chiron at the helm? An abusive oarsman takes swipes at the beleaguered and meek more often than the vile and grotesque. Passengers come to blows over seats. Impudent litter and graffiti are banal scenery.
While it's probable that Chiron crossed the Styx at one time (since he died after losing his immortality), it seems unlikely that he was allowed to drive. I believe the writer of this letter meant Charon.
Maybe this BuboBlog mythology refresher can help.