I particularly like the end of the post where he compares the history of nuclear fission to the progress on quantum computing. Traditional encryption might already be broken but we have not been told.

In a world where spying on civilian communication of adversaries (and preventing spying on your own civilians) is becoming more critical for national security interests, i suspect that national governments would be lighting more of a fire if they believe their opponents had one.

They absolutely are. NSA is obsessed with post-quantum projects atm

tbh they could just be pushing for people to adopt newer, less-tested, weaker algorithms. switch from something battle-hardened to the QuantResist2000 algorithm which they've figured out how to break with lattice reduction and a couple of GPUs like those minecraft guys did.

But is this because they are already needed or because they want to preserve encryption for past and present data post-quantum?

The latter

NSA is pushing for PQ algos.

I really doubt we are anywhere close to this when there has been no published legit prime factorization beyond 21: https://eprint.iacr.org/2025/1237.pdf

Surely if someone managed to factorize a 3 or 4 digits number, they would have published it as it's far enough of weaponization to be worth publishing. To be used to break cryptosystems, you need to be able to factor at least 2048-digits numbers. Even assuming the progress is linear with respect to the number of bits in the public key (this is the theoretical lower bound but assume hardware scaling is itself linear, which doesn't seem to be the case), there's a pretty big gap between 5 and 2048 and the fact that no-one has ever published any significant result (that is, not a magic trick by choosing the number in a way that makes the calculation trivial, see my link above) showing any process in that direction suggest we're not in any kind of immediate threat.

The reality is that quantum computing is still very very hard, and very very far from being able what is theoretically possible with them.