So-called "surveyors" screw up more such jobs than is ever really justified.
Old Artex is not terribly hazardous in the first place. It certainly isn't when isolated.
With hindsight, I would have removed all of the Artex, and called him back in to witness that it had been removed. I guess what he's worrying over is that only the damaged bit was removed.
All you can do now is wait until the report has gone in, and challenge it. In my opinion, the "hazard" has been contained by isolation, but I'm not the one "ticking the box".
It's the lenders of course who decide whether to release or not. But, in today's ever so safety-conscious world, they would normally go with the surveyor.
See what he says, and do come back to us.