The toilet will not flush because the sewers are full & flooded. Flushing only causes the toilet to overflow.
Beyond that, these people are pathetic. They had ample warning to evacuate or to stock up on food & water. Perhaps a few days of empty bellies will give them a clue about the next storm: You cannot stay in a house that might flood, you MUST move to higher ground & be prepared to stay there for several days.
I don't know about the outlying suburbs but the sanitary drains in Manhattan go directly into the rivers with no treatment. Can you imagine the "water hammer" shock when you flush a blivey from 100 stories up when it meets the elbow on it's way to the Hudson?
Regards,
GtG