A homeless, “emotionally disturbed” man with nearly a dozen prior busts stabbed a 51-year-old straphanger inside a Greenwich Village subway station during the Thursday morning rush – knifing him in the back moments after the two feuded on board a train, cops and sources said.
The two men – who did not know each other – clashed on board a Brooklyn-bound D train at West 4th Street around 7:30 a.m., cops said.
As the pair got off the train, the suspect – later identified as Justice Jackson, 30 — knifed the victim in the back, cops and sources said…