I disagree. I think you give the writer too much credit. A natural reading of what's written is that it is impossible to break Bitcoins algo in this universe.
Quantum mechanics is very much part of this universe.
Disclaimer: Not even an armchair scientist.
The threat from QC is that Grover's Algorithm greatly reduces the space you need to search for solutions. It is impossible to brute-force a problem with 2^256 solutions, but it is a lot easier if you can effectively make the problem smaller, and that is what Grover's algorithm does.
Mmmmkey, what's your point?