I think she is doing this at he behest of DeBlasio, just to piss Cuomo off and make his reelection difficult instead of a coronation.
That’s how much these two guys hate each other.
Yesterday, in a conference call with reporters, Cuomo was already blaming deBlasio(for the possible Nixon challenge).
https://www.nytimes.com/2018/03/07/nyregion/cuomo-cynthia-nixon-de-blasio-governor.html