Yep, but I addressed that in my post by saying the only reason they would do that is if they think the Lakers landing him was imminent (e.g trade deadline) and wanted to go all in on AD. The Celtics preference will be to wait until the offseason to pair him with Irving, and imo NOLA would be able to get a much better package from Boston even if Ainge managed to keep Tatum out of the deal and they could still potentially compete the year after with some combination of Holiday/Hayward/Randle/Horford/Mirotic/Moore/Brown/etc, or they could blow it up and find a 3rd team who wanted to take on some of those guys in exchange for assets and potentially move Holiday at the same time, or move him in a later deal.
If Mitchell was actually capable of playing PG then we would've seen plenty of it already with Rubio's struggles early and Exum's struggles most of the season, but we haven't because Mitchell can't run the point.
The Exum/Korver/Ingles/Crowder/Favors lineup was originally tried with Mitchell there in the first couple of games after acquiring Korver, but DM tunnel visioned too much for the lineup to really work, whereas it hums along much better with Exum since he's not looking to score every possession and it allows everyone else to get involved more, particular Ingles who gets to actually showcase his playmaking skills with that unit alot more, and it results in a lot of wide open 3s and wide open lanes for the Exum/Favors PnR to operate. OKC defended that lineup the best so far as they just stayed home on all of the shooters and let Exum try to beat them by walling off the Exum/Favors PnR, and that's where if Mitchell was a more willing passer then he could absolutely abuse that style of defense since he could take and make the shots Exum can't, but it doesn't work because with Mitchell there they just lock him down instead and he wasn't able to find the open man or keep the offense rolling in the half court and instead would force a lot of bad shots.
It's still imo the biggest thing preventing Mitchell from being an all star caliber player, even moreso than his inability to draw fouls. A Mitchell who can play point for stretches of a game like DWade can/could would unlock so many more lineups for this team but he's just not capable of doing it at this stage in his career, and I think it would dramatically improve his efficiency since he could pick and choose his spots better instead of forcing tough looks.