The hypothetical plane can only carry a dozen people at a time and burns a lot more fuel per mile than a comparable subsonic aircraft, so the tickets will be very expensive. Most people will not be able to justify the cost, even most business travelers.
Unless the cost of oil goes down dramatically, the only way for hypersonic flight to become affordable for the masses is for new technology to achieve drastic fuel savings. If that happens, there would be no reason to oppose it any more than one might oppose "regular" air travel today.
Commercial airlines have an extremely strong incentive to reduce carbon emissions, more so than virtually any other industry. I wouldn't worry too much about aviation tech moving in the less efficient direction.
Except they didn't even correct correctly. GP said "We need to find ways for people to burn less carbon," which is totally correct. "Carbon" is being used as a mass noun.
I don't know if you are referring about my comment "fewer hydrocarbons", but it was a direct reference to the post I was referring to, "cool way to burn hydrocarbons". I wasn't trying to be pedantic or correcting anybody. Maybe I should have said less, but... I just didn't. The point is simply that higher efficiency doesn't directly equate to more usage; though it can in some cases.
Okay, but 9 Mach is a lot. And flying higher also burns more fuel to reach that altitude. Not sure which of the effects dominate though.
All in all, I'd be extremely surprised if this technology reduces fuel consumption.
The only mention in the text about fuel usage is that they need to use a special engine with lower fuel consumption to even be able to put people and equipment on the plane. Why don't regular jets have that problem? Because they don't consume that much fuel.