This can be a mutually-beneficial transaction -- the powerful entity that needs to manage perceptions gets a boost, and the participants get a reputation boost for being seen involved in powerful circles. Witness that the HN poster's business is being promoted, just by being invited. (Which is a potential conflict of interest for the experts, if they're supposed to be representing some truth or public interest, but they probably have to play along for this personal boost.)
One thing that can possibly upset this transaction is if there's a channel for uncontrolled speaking out around it. Say, the format is a televised/streamed roundtable, and an expert with the mic decides to burn bridges with the organization and others like them, while saying things the organization really doesn't want them to say. (The motivation could be altruistic/duty, or calculated career grandstanding.) Or, in a tightly-controlled format, the expert who wants to never be invited to that kind of thing again could attend and then immediately bite the hand that just fed it, by ripping it on Twitter/YouTube/Medium/news/op-eds/etc.
I've seen a lot of experts play-along for their careers (in this kind of thing and analogous transactions elsewhere), and sometimes you see modest amounts of pushback by people who are still playing a political game, but rarely you notice a person who won't get on the slippery slope of game-playing at all yet who manages to have impact there.
(Personally, I'd be a terrible politician even if I wanted to be, and I just want to quietly solve technical and societal problems, while someone else fronts the band.)