Yes I agree with the others... pretty much any suspension of a public service is going to hit poor residents the hardest.
That being said, Metrorail tends to be used by relatively high-income users (moreso than the heavy rail systems of other cities) whereas the bus tends to be used by more middle income people. So if there were a bus shutdown, that would hit poor residents much, much harder.
Another (good) thing is that in DC, the income differential between transit users and other commuters is pretty low -- anywhere from 3-10% depending on jurisdiction. Compare that to a place like L.A. where the income differential is more like 40%.