I agree with almost everything Cassius said, except for a slightly different take on the hypothetical being a purely logical argument. I take his formulation as a counterfactual, similar to when he said if all pleasures were distributed over the whole person and of the same intensity, they would all be the same -- there, he was asserting that pleasurable feelings _do_ have variety. Because of his observations.
I think it's similar here-- by presenting a counterfactual, he is saying he hasn't observed such a strategy succeeding. That partying doesn't relieve fears of the supernatural-- according to his observations.
Of course, yes, embedded in that formula is also the supremacy of pleasure as the goal, and his condemnation of the strategy because it fails at pleasure. But his point is more about his observation on the strategy and its failures than on logic and hypotheticals.