That doesn't sound SO bad. Selection criteria seems like a major issue here, and the author only talks about the validity of the results.
Why do we care about physics? Or psychology? There are answers to these simple questions, but I don't think the answers inform the selection criteria. We don't care about physics because academic researchers need to publish papers or get funding.
Having any old non-expert on the panel could be problematic. Especially if they become political tools, and right now they'd definitely become political tools. But it would seem reasonable to me if there were adjacent experts. What do engineers or chemists want to see in physics? These aren't hostile interlopers. But if nobody outside a field cares about a line of research, or trusts a line of research, then maybe that's a bad line of research.