I personally believe that Micheal, through all of his and his fathers experience, had anticipated atleast the possibility of Geary's outrageous outburst/demands, and put together a contingency plan, ie implicating the senator in a murder at Fredo's brothel.

Though it was an effective strategy, Roth had perhaps secured the more powerful piece in Questadt. Vito maybe would have made a stronger point not to allow this to happen - we see from the reason he gave not to take the Sollozzo deal that he was very careful not to jeapordise his contacts or any future ones.