Disagree, tbh. Perhaps Pop of 10 years ago would freak out about every turnover a young player makes. But that's not how Pop coaches anymore
, Nando De Colo was far and away the most turnover-prone player in the NBA as a rookie and he still got almost a thousand regular season minutes. Present day Pop lives with turnovers as long as they are of the aggressive variety. It's part of way Cory Joseph was never that great of a fit: he was great about taking care of the ball but Pop doesn't really care about that. I think he's learned from Manu that to be a creative player you have to live with turnovers.
Now, obviously, the most likely scenario going into next season is Simmons not playing much. He has such little experience at a high level of basketball (this summer league is the highest level of basketball he's ever played -- he never made a training camp or even a summer league previously) that it's going to take a while to adjust. Whether he's capable of adjusting his game to NBA caliber athletes will determine how he proceeds -- not turnovers specifically, at least under this version of Pop.