You mean aside from the essentially unserious nature of his fiscal proposals, which promise to balance the budget by cutting both spending and revenue in such a way that the numbers don't come anywhere close to adding up?
I'm familiar with the Laffer curve, but I'm not sure what point you're trying to make. Under every incarnation of the Laffer curve that has even a passing acquaintance with empirical data, the Ryan tax cuts will sharply cut overall government revenue. That's because the US is already far to the left of the revenue peak. (Indeed, it was already to the left of the peak during the Reagan tax cuts, which also failed to increase government revenue. There's a reason even George H. W. Bush called it "voodoo economics".)
There is no plausible mechanism by which any versions of the Ryan plan we've seen can actually balance the books. It's nothing more than a generous gift to the country's most affluent taxpayers couched in hand-wavy ideological nonsense.