That's the pic that someone posted earlier and I just reposted it. It says the source is HBO.
I've learned that many things that don't make sense are a result of shit writing. We come up with these explanations for things, but we then find out that the writers truly are incompetent (i.e the Jaime raping Cersei in the Sept scene, where the writers stated they never wrote that scene to indicate Jaime was raping Cersei).
My personal belief is that Dany is in a position where she can't risk losing a key ally in what is a crucial point in time. Any other circumstance and Dany would have dealt with her, but she isn't exactly in a position where she can do that yet. Dany executed that advisor of hers that murdered the imprisoned Sons of the Harpy fella, because he took the law into his own hands and murdered a prisoner. That guy was guilty as fuck, and yet Dany forbade his killing until a trial. The killing of an innocent child should have her raging, and so should Tyrion for that matter. The fact that Tyrion isn't, tells me this is nothing more than a cheap way for the writers to acknowledge that Tyrion knows, but then stupidly ignore pre established character traits.
Also, Shireen and Marcella are completely different situations. One was killed due to a blood feud between two families, and the other was offered up as a sacrifice in a ritual. Even if the intent is for Dany and Tyrion to not dwell on Marcella's killing for now, Dany flipping out over Shireen would still not be out of place. All in all, I think this a failure in the writing and not indicative of any change in the character.