Same thing happened to me earlier this year with a dealer SOR car and it was quite frustrating. One of the reasons given was that 'the new buyer doesn't insist on a inspection', so either they wanted to avoid the hassle or there was something to hide.
So I would assume in your case the new buyer is paying more and/or they do not want an inspection. If they are paying the same then perhaps they should get it inspected
As others have said this happens all the time unfortunately. I'd sleep on it and I'm sure that tomorrow you won't want to spend any more time/money on this chap.