The only way this makes any kind of sense is that Luka said he would absolutely never resign with the Mavericks. His contract is up soon, as far as I can tell. But even if that was the case, why wouldn't you shop him around? AD is a great player but he's over 30 and gets injured a lot and isn't in the same tier as Luka. I have to believe you could have found a better team with some other team.
It also doesn't really make sense for the Lakers as a team looking forward unless Lebron is retiring soon. I mean, I guess Kyrie and Luka were working out sharing but Lebron isn't as good a shooter as Kyrie.
Just seems weird all around.