Ah The Shusher, an interesting creature of the mass transit system, The Shusher is a loner, running with no wolf pack. They cringe at the thought of human contact on the way to and from work. It makes you wonder if they ever talk to anyone, or if they live shutoff from society for the most part.
Have a crying baby? Shush. Want to talk quietly to your friend? Shush. Yes, The Shusher is a no nonsense traveler. You're tempted to point out to them that they willing boarded a train that makes plenty of noise without the passengers, but that might pull them away from their romance novel and set them off on a tirade.
Occasionally this person will be in the "quiet car," at which point it's somewhat acceptable for them to "shush" people, but frankly they need to just come to grips with the fact they aren't getting complete silence on their ride.
There will be the rare occasion when The Shusher is an under-appreciated vigilante of sorts. When you end up stuck on a train with the person yelling to their friend from a foot away, The Shusher will step in. This will be a rare occurrence, as most times this passenger is just way overreacting.
So to The Shusher, if you would like total silence, might I suggest driving to work rather than the train. Also be forewarned if you "shush" me, I will pull an "Always Sunny" and plaster the city with "rude man who shushes" wanted signs until I find you and get retribution.