A little more context on this from Chris Mannix:
https://www.si.com/nba/2020/11/23/nba-free-agency-best-worst-dealsWhile I don't always agree with him, and have some gripes with what he says here, the most important point he makes is this: we don't really know what the dynamics of the the discussion with IND were.
For example, I seriously doubt Hayward had the final CHA offer in hand, then went to Ainge and said: "I'll take a year and $45MM less (guaranteed) to go IND if you work out a trade", then Ainge was offered Turner and Doug McD and turned it down.
I also doubt Ainge had a deal a) he would have been pleased with, and b) Hayward would have agreed to, if Danny had just acted faster. That suggests CHA was really late to the game with that ludicrous offer.... which I don't buy. They've had interest in Hayward for a long time -- they probably made an initial offer at or before the 6pm deadline Friday.
Lastly, it's totally possible Ainge just didn't want Turner that much. He may have seen Warren or VO has more valuable to the Cs, and / or didn't want to pay Turner and McDermott knowing the Tatum extension was coming, etc. It's very possible he knew he was signing Thompson, and feels he's a better cure for what ails this team. Or he may simple have wished to wait and see what else is out there this year (assuming he in fact pulls a TPE out of Charlotte).