I'm assuming he/his agent have a plan here.
I did think it was odd how during the combine process he opted to not play in the scrimmage as someone who was projected to go late second/undrafted. I know many players would rather go undrafted than be taken late second round because the money isnt guaranteed at that point and going undrafted they at least get to pick where they go.
My suspicion is there's a team thats shown interest in him early in the draft process that would put Tristen in a spot he wants to be in. They had a deal that if he was available late in the draft or went undrafted he would sign with them (which is why he didnt take part in the scrimmage, to not give any other team a reason to blow up that plan). Pacers took him and blew up that plan.
Maybe he didnt see NBA time available with the Pacers and something opened up with the original team he had in mind? My optimistic thoughts. Or maybe he made a completely emotional decision with no plan whatsoever. Guess we will find out.