I think that the current Israeli government wanted to float the idea of redrawing the boarders along ethnic boundaries. However, if Netanyahu did it himself, it would immediately become the new negotiating position, which is a more serious statement than he wanted to make. So, he delegated the FM to present this idea, which has been discussed to a degree in Israel, but is largely unknown in the rest of the world. By presenting it to the UN, the Israeli government can be sure that it will be a headline around the world tomorrow, while Netanyahu can maintain plausible deniability about supporting it. In other words, standard political diplomacy.
Report: Car bomb kills 10 in Syrian port city (AP)
from the article: Aluf Benn / Lieberman is making a liar out of Netanyahu