I will say that if there is something pretty obvious that I missed on purchasing something, I'll kick myself and take my lumps.
But, I agree, this seller was a real clod to indicate the frame was like new with such a huge repair. And, I hope that if I ever start selling stuff, I'll stand behind my anything I sell.
As others have mentioned, it is quite likely this frame will be just fine. It appears as if the repair was feathered quite well, and I'm assuming it used copious amounts of carbon fiber wrap.
Now, the question is what the original damage was.
Drop something on the frame? Could give a single impact damage without significantly affecting the rest of the frame.
Front-end damage? Running into a parked car? The problem with that kind of damage is that inevitably multiple tubes are damaged, even if it only appears as if one was damaged.