The point isn't "pea shooter" as a description of state of the art, but of its effectiveness. There's nothing we have available to us in technology that would be able to divert a mass-extinction class meteor (or even just a really-bad-day meteor) on short notice. Given a decade or more we might be able to launch a mission to moderately divert an orbit, but at very high expense.

It's the cost-to-effectiveness ratio I believe TSA is being compared.