I absolutely agree. Of course every witness under oath should tell the truth, regulated professional or not. And I know that being a regulated professional doesn't guarantee truthfulness, Upton being the obvious example of a doctor under oath who was economical with the actualité.
I'm just reiterating CM's point that R1 hasn't taken the risk of exposing any of its witnesses to a potential decision between their professional integrity/preserving a certificate to practise and pissing off a current employer.
Given that the GMC doesn't appear to give a toss about Upton who has buggered off abroad anyway, perhaps the respondent needn't have worried.