When Lieberman incites against the Haredim, Netanyahu goes into silent mode and makes himself like the status of a deaf, mute and child. But when Lieberman opens his mouth against the Right and against the Settlers, Netanyahu goes out of his way to appear as the defender of the Right Wing public.

  -- former MK (of Shas) Rabbi Shlomo Benizri

Benizri is correct, but in Netanyahu's defense I think the reason is that Netanyahu has always been careful to not try to poach the Haredi voters away from the Haredi parties - to not "vacuum them up with a straw" as they say in Hebrew, and he also treats the Haredi parties with great respect and treats them fairly. Netanyahu has treated the Dati Leumi parties with derision, especially during coalition negotiations but also during governance, and has put forth great efforts to poach their voters during elections. Netanyahu does not need to defend the Haredi parties, but if he wants to continue poaching the Dati Leumi voters he needs to appear to be the great defender of the Settlers otherwise they won't consider voting for him..