It isn’t an exclusionary filter, it’s a standard of quality:
Science’s job is to fill up the silos of the world with the grain of useful information, and we’ve found that applying the principles of the scientific method and operating under the guidelines of methodological naturalism means we’re productive: we can keep trundling up with wagonloads of corn and wheat and rice. The creationists are showing up with broken-down, essentially empty carts, containing nothing but chaff, a few dirt clods, and some fragrant manure, and they’re being turned away because they have nothing to contribute. You’re not being excluded if you have nothing to offer.
