This is 100% speculation, but when Cody beat Sammy for the belt I saw a lot of online comments like "RIP to Sammy's completely forgettable TNT title run" or something to that effect. It could be that AEW knew this, and since the TNT belt has made all previous holders look super strong, they wanted something to give Sammy's title run a little more "oomph"

It wouldn't surprise me if Cody (knowing how the fans feel about him) set it this all up give Sammy a stronger run. Beat Sammy a bit unexpectedly, do the interim thing, cut an over the top "Cody" promo, and then put Sammy over in an insane gimmick match.

Technically, the belts flip flopping, but because Cody never even defended the belt (i think?), it really just feels like a longer feud between the two, with Sammy going over and still the champ.