Well why should he resign? Shouldn't he fight the system from the inside? It's a lot better then just resign and tell everybody to screw off.
I personally agree with Lieberman in a lot of things. A secular nationalist party would be good for Israel. But Likud controls the government so it's their fault for everything that is happening.
Yes it would be good for him to stay and do what is needed from inside rather then quit. This is a sad fact of what Rabbi Kahane tried to do, was imprisoned and then banned by the union of the fraud "right", fraud religious "right" and the entire Left.
A secular nationalist party would be much better then a fraud right (Likud) or any of the Left. I'd like to personally see Michael ben Ari advance to the position of power. ;o)