I am perplexed as to your opinion of how when an expert is paid for his analysis, that makes him "bought" by the engager?
It's called professional integrity mate... there's not much of it left these days by the sounds of it.
A true expert with a valued reputation can't be "bought" by anyone.
There are many other times where the ATSB has made questionable findings and I often read about them in the media and pprune for starters.
If you want, I can put you in touch with the expert engineer and you can both thrash out your theories. I know who will win with experience.