I think the Tahoe assassination would give Roth plausible deniability. Michael just had a good meeting with Ola, a bad one with Frankie, so it looks like Frankie made the hit. If Michael dies in Havana, everyone will assume it was Roth.
I always assumed that Roth would use his association with Batista to ensure that Michael's death would be blamed on Castro and his rebels. It was a very chaotic time in Cuba.
