I think retired players are a part of these meetings all the time. It might be something where Tim, the franchise player, is there to tell him what it was like and how him leaving means it's KD/LMA/Kawhi team now.
I don't think the meeting has anything to do with his decision IMO.
I think he retires - otherwise doesn't make a ton of sense. Tim has shown that if he's playing, he wants to win. If SA fell short last year he knows they need money to add to the team. Him opting in means they have less chance to build a team if he does not retire.
If he opted out (assuming he was coming back), he could have gotten paid more than his opt-in if SA whiffed on FA and if they had to renounce Tim's cap hold to get the cap space and he had to play for the min, I don't think it would have mattered to him.
We will see - a lot of this is confusing to me.