IMO, it wasn't so much Tyrion (although he planted the idea) as it was Daenerys being completely unrepentant about the massacre of the civilian population of King's Landing and then to continue that she wanted to liberate the rest of the world and that they would have no choice.
She died fast though didn't she. One quick stab, while Arya got much worse by getting repeatedly stabbed and falling into the filthy water and still making it out alive. lol
I think Dany’s quick death was befitting. Arya is a tough girl inside and out. Dany was just an entitled girl with a famous last name and dragons. She’s as useless as Sansa in a battle.