Right but Mach 1.0-1.3 is all that "Boom Supersonic" is claiming to hit, though, so the paper is in line with the marketing pitch. The speed advantage of "up to Mach 1.3" might not be worthwhile, no, but that's orthogonal to the claims of "boomless" supersonic.

Now the article randomly pulls Mach 1.7 out of seemingly nowhere, and I have no idea where that came from or how that is justified. But the company isn't making that claim as far as I can tell ( https://boomsupersonic.com/boomless-cruise the "FAQ" section even specifically says: "Boomless Cruise is possible at speeds up to Mach 1.3, with typical speed between Mach 1.1 and 1.2.")