Journalists will often try to attend these things to get a scoop, the other attendees will be trying to influence that scoop. That may not definitely be the case here, but it's also not given they're plants or anything.
Because he's a controlled opposition nepobaby with little actual intellectual merit, like many in the sector. Similar to Sam Harris, who's also on the list, with new atheism. Sometimes you just need some people to propagandize and all that's important is that they're loyal.
He's there just to make a certain group of people slightly more okay with some questionable views.