This would be easy to find out given that their names are public and so are the projects/papers/publications. What does the data indicate?
Seems it takes a high-ranking defector to suddenly get everyone sweating and carefully walking back written statements.
What information are you referring to that's not public? Most scientists' research areas, publications are public knowledge. Science relies on this to make progress.
OP claimed people signing the letter had a conflict of interest and/or were somehow complicit. Rather than getting into an argument, why not put forth the data. I'd suggest OP to look up their names, papers, labs, funding sources, etc and put forth a real argument.