According to Roth's plan, Michael would be dead the night of Tahoe party
So why would the ever astute, meticulous Roth as clever as he is, take such an uncharacteristic risk, showing his hand interesting himself in an obscure beef - between Miami, New York, Nevada and Havana - seems to me far too high a risk for Roth to take especially so early on when by all accounts Michael would be dead the night of Tahoe party
The Rosatos were essential to Roth's Plan A--to have Michael assassinated at Tahoe. By advocating for the Rosatos against Pentangeli, Roth in effect set up Frankie to show up at Anthony's party, contentious and angry. Therefore, Pentangeli would make the perfect patsy for Michael's assassination. If Michael had been killed, Pentangeli either would have been on the run, or would have had to fight the Rosatos for control of the Olive Oil business. Either scenario would have weakened the Corleone successors.
Even though the attempt failed, it still looked like Pentangeli had set up the Tahoe shooting--that is, until Michael finally came to his senses and figured out that Roth was behind it. That's when he started playing Roth beautifully, telling him (in Miami), that their Havana deal was still on, and that "Frank Pentangeli is a dead man--you don't object?" Roth fell for it, hook, line and sinker. Now Roth's greed for the $2 million blinded
him to the obvious: Why would Michael ask Roth's permission to kill his own subordinate, Pentangeli?
