I think he is saying if someone skilled and knowledgeable in the area of the expert witness' testimony shines a light of truth on such testimony it must stand up to the scrutiny. If it does not then you are not being true to your knowledge and are being misleading on purpose to get paid. He argues all such testimony, good or bad, must be a part of your public record so we have that opportunity to examine your body of work. This seems reasonable when your work has the potential to deeply impact groups of individuals or the public.