I am amazed and disappointed that anyone working within the profession could take such a stance and it shows what a long way some auditors have to go to work ethically and professionally. Thankfully I guess this auditor is very much in the minority and I hope that they move on to other work or learn from their mistake.
it's vital that auditors share their views when they find something which may represent a deficiency. The auditee needs to know what could be wrong and why, and be given the chance to provide other evidence to demonstrate compliance if it is available. They need to know what is wrong and why it's wrong so that they can undertake effective root cause analysis and identify suitable corrective and preventive actions. They need to know what is wrong and why it's wrong because it's common courtesy.
I spend a lot of time teaching audit skills and one of my lines is 'no surprises' - encouraging auditors to share their views openly and honestly with the auditee and to build an effective working relationship and to work together to determine the final wording of any findings. That's the right way to go in my view!
So what can you do if you are unlucky enough to get an auditor who raises a finding in a report that you've not been appraised of? Firstly complain to the certification body. They employ the auditor, it's their responsibility to make sure they are working professionally and ethically in line with the requirements of ISO19011 and ISO17021. Secondly ask for a new auditor for the next visit - you don't have to accept the same guy again. Thirdly learn to ask whether the findings raised at the closing meeting are the totality of the findings which will be reported. Happy auditing!