A man accused of stabbing a stranger to death during a fight outside the Port Authority subway station last week is back on the streets after a Manhattan judge set a paltry $100,000 bail in the murder case, over the objections of prosecutors, The Post has learned. Jesus Ramirez, 28, was freed from Rikers Island Saturday after having to float just 10 percent of a $100,000 partially secured bond for the caught-on-camera slaying of 49-year-old Guarionex Torres in Hell’s Kitchen, records show.