I think the elder Mr. Netanyahu would ask for respect, at least during the mourning period of shiva. I do not think he would want people to "parrot" polite sayings, but having said that, it IS a grave sin to speak loshon hora about another person, especially when it's about another Jew, and especially when the person can no longer defend himself. If you don't believe me, read the Chofetz Chaim.
Saudi king to meet with Obama on Friday amid Gulf concerns over Iran deal (Reuters)
from the article: Benzion Netanyahu's death - researching the past, predicting the future