How? Using super noisy rocket next to a population center which can start only during outstanding weather in launch and landing area and when things go wrong it can explode with power comparable to tactical nuclear weapons?
You can go and revive Project Pluto, it will be less dangerous and more predictable.
And for sure, the 150,000 pound weight of this "Stargrazer" vs the 11 Million pounds of SpaceX's starship certainly reduces it's blast radius!
I didn't say it'd be great, just that SpaceX more likely to be first (and no, I'm not a fan of Elon, used to think he was doing great things, but he's obviously decided that supporting autocrats & trolls is more important).
The 20,000 RPM rotating detonation engine doesn't seem exactly quiet, so they'll likely need regular jets in addition to the rotating detonation engine and rockets; not exactly simple.
Meanwhile, SpaceX could solve lots of those problems by landing further away from the cities, which will negate much of the fast-trip advantage, and so leave a good market opening for 'Stargazer'.
If both work, I'd probably rather go with Stargrazer, but I still expect SpaceX will be first (unless it goes the same way as the sub-5-minute battery-pack-swap feature on the Teslas...)
You can go and revive Project Pluto, it will be less dangerous and more predictable.