I see this as D&D taking another liberty, this time a smart one along the lines of the Hound/Brienne and Arya/Tywin matchups.
Tyrion is disguised still, he's been bought by Hizdahr, that seems to be clear. This will be very exciting for the audience, who regularly cheer for both Tyrion and Dany. Now they will be torn between this conflict - or is there a conflict? We'll see.
If Dany still rides off on Drogon, unaware of who Tyrion is, I would say D&D made a smart move, but let's see how it all plays out, first.