Meyer completed a PHD dissertation on origin of life biology. I would think that qualifies him to offer valid opinions on biology but I wear a blue collar and work boots so what the heck do I know.
He is attempting to comment on specific disciplines in biology, namely molecular genetics and development. While he is qualified to evaluate logical flaws in arguments, unless he is currently working in either of these fields (or has within the last 5 years, since these disciplines are rapidly evolving - no pun intended), chances are he is quite ignorant of the effects that mutations in specific genes can have on the embryonic development and normal function of these organisms. It would be akin to a WWII pilot attempting to advise the pilot of one of today's jets. While basic principles of flight remain unchanged, unless he had been working in the field recently, his insights on the finer points of today's technology would be hopelessly out of date.