It's an interesting question which is, as you suggest, difficult to answer absent sight of the evidence. However, my thinking is that the decision-making progress in bringing the charges may form part of the case because the question of "good faith" in the allegations is subjective.
That is to say someone at the PL has looked at the evidence and formed the opinion that City's actions constutute dishonesty. Whilst, obviously, it is ultimately for the Commission to decide, as it's implicit in the most serious charges, it would seem to be legitimate to cross examine whoever made that decision to bring out whether that opinion was arrived at properly.
Unlike, for example, the Secretary of State who, because (s)he can't see everything, is accepted as being able to delegate that power to their civil servants, I don't think Masters can shift that responsibility. Given the seriousness of the case and all its implications, he absolutely must have signed off on it and, therefore, should be able to justify it.
City, may, of course, believe that the decision-making process was impeccable or that there is nothing to be gained by challenging it but I suspect not and that Masters will end up being cross examined. I certainly hope so.