I don't know what the big deal is. Espn is reporting that there was a huge group of people involved in KC's interview team that went to KC. Him being there first doesn't mean he was running the interview or even doing anything more than sitting there listening and taking notes.
I have interviewed people for jobs with others present who were not going to have one iota of influence in the hiring decision. There were many reasons he could have been there.
If you thought that Clark had cut ties 100% with Pioli, then I'm sorry, but he is still in the role of GM. I think he has been stripped of much of his power (hence the lack of any word about negotiations with Albert or any of our other FAs). The deal will probably be Pioli can stay to help handle contract negotiations, but the decision of which players we go after would remain with the coach. If the coach doesn't want that responsibility, then they would cut Pioli and get a new GM.