You've just moved the goal posts from someone who can be crossed in court to someone who can't, which is worse, because then you have now way of verifying that the "independent" certifier is actually independent or that the certification was properly done.

You still need to allow the "independent certification" to be examined in court to validate both the independence and the certification. The means testimony on the applicable standards, and how the specific equipment used satisfied those standards. And right now, the expert witness already does the latter with respect to calibration, etc., for the equipment they used.