I'd agree with your conclusion, but it's moot. A cyptographically relevant quantum computer is physically impossible.
Discussion
You should present your proof of this claim to the world so that we can save countless time and resources.
Your asking me to prove a negative and you quantum believers are the ones who lack proof. You want to invest in my perpetual motion machine? Prove I can't build one. Don't trust, verify. We can talk about quantum resistance when the first shor pops. We will have plenty of time before they can make it economically scalable, if that ever happens, which it won't, because that's not how the universe works.
I'm not a quantum "believer" - it sounds to me like you admit that it can neither be proven nor disproven.
Thus claiming it's impossible is just as much bullshit as claiming it's inevitable.
The difference is that I am not advocating a drastic, risky, insecure modification to the Bitcoin network based on my opinion. I think the burden of proving it IS possible is on you. Since you agree that your position is unfalsifiable bullshit, let's do nothing for now