Well, if he told the management of Apple and the Bank of America what to do, I didn't notice. Which is quite plausible, I might very well not. But did you?
Passive investing usually refers to buying index-only funds or investing with no voting powers.
It also refers to investing where you don't try to exercise powers, despite having the ability. And if you invest a ten-digit sum, you do have the ability. Money talks.
Buffett is pretty much the definition of an active investor, in that he picks companies rather than putting money into everything.