The simple answer is FiOS did not want to put much money into FiOS1 news. Going with RNN who's TV channel only broadcasts one show which ironically is simulcast on FiOS1 news and has a studio was a cheaper way then building a studio.
Thing is they promote Fios 1 as "Long Island's Freshest News" on various billboards. Either way Cablevision is still worse, with yet another channel blackout, this time WPIX, which should send new subs over to VZ.