I will reply directly r.e. the analogy itself here. It is a poor one at best, because it assumes ML-KEM is akin to "internetting without cryptography". It isn't.

If you want a better analogy, we have a seatbelt for cars right now. It turns out when you steal plutonium and hot-rod your DeLorean into a time machine, these seatbelts don't quite cut the mustard. So we need a new kind of seatbelt. We design one that should be as good for the school run as it is for time travel to 1955.

We think we've done it but even after extensive testing we're not quite sure. So the debate is whether to put on two seatbelts (one traditional one we know works for traditional driving, and one that should be good for both) or if we can just use the new one on the school run and for going to 1955.

We are nowhere near DeLoreans that can travel to 1955 either.