It's like using different technologies to protect against nuclear waste leaking from storage. Each plausibly suitable layer of a different sort makes a leak le

It's like using different technologies to protect against nuclear waste leaking from storage. Each plausibly suitable layer of a different sort makes a leak less likely. Post-quantum algorithms are, as yet, young and very possibly poorly understood. They may even offer no security at all (due to presently unseen flaws); therefore as a hedge against that include at least another currently in use and current best practice algorithm so that at least _that_ level of security is retained. Plus, as I pointed out several replies ago, if the current (and fast since reasonable key size Elliptic Curve based) algorithm is the outer layer it can be validated quickly which is a better guard against denial of service attacks and other poor fakes.