> I am very cautious about the "modulo engineering scaling" carve-out

As OP said elsewhere[0, 1]:

> Once you understand quantum fault-tolerance, asking “so when are you going to factor 35 with Shor’s algorithm?” becomes sort of like asking the Manhattan Project physicists in 1943, “so when are you going to produce at least a small nuclear explosion?”

In other words (IIUC): Some problems (here: scaling fault tolerance) seem to be easier than others.

[0]: https://scottaaronson.blog/?p=9665#comment-2029013

[1]: See also https://news.ycombinator.com/item?id=47959531 for a very similar quote.