Koeman's camp = Koeman and his workers/staff/assistants. I'm not saying he has any sort of power, I'm just saying all it takes is one or two people from his staff to leak info to the media and you have a story. No sort power needed, just poor character. It's not just this forum, quite literally pundits are keep asking why he isn't playing specifically because his cameos were impressive. It's obvious that after these performances people would start pressuring him even more about Puig not playing. The fact that these rumors are surfacing immediately after these performances is suspicious, because it specifically justifies his squad role as the question is no longer about his performances.
Also remember, Koeman and a member of his staff have a history of doing this in their previous clubs.