Godfather II: THe US Senate Hearings/Investigation

When Michael Corleone is hauled before the Senate investigatory commitee, and questioned about his sources of income, he replies that “I own some stock in some casino companies, but aside from that I have no interest in any casinos”.
How is this so? Earlier, Michael meets with the slimeball Nevada senator (Sen. Geary), who gives him the going price to acquire another casino license-and the Corleone family did acquire the unfortunate Moe Green’s hotel/casino (after Moe catches a bullet in the eye).
In any case, these congressional hearings are mostly for show (IMO), so the senator asking the questions would have known all about the Corleone family’s Nevada operations-so why didn’t he embarrass Michael on live TV?
Or had the family lawyer (Tom Hagen) done a bang-up job in hiding everything (through silent partner ownership, etc.)?

The family lawyer (Tom Hagen) did a bang-up job in hiding everything (through silent partner ownership, etc.)