Buddhism says IS and ISN'T, at the same time, is the truth. So people exist, but not as what they appear to be.

Nihilism does not affirm any IS-ness at all. Nihilists say people simply do not exist.

So no, Buddhism is not nihilism, Rinpoches are not nihilists, you are taking half the teachings and thinking you leaned everything.

Is & isn't, at the same time. Quantum. Duh.