Admittedly, a meat mask would have been more safe than just walking around like she did...I mean she'd be easily identifiable, but at least the waif would have to decide "Ok, I'm going to pursue the person mocking all vegetarians, since she's the best lead I have on Arya."
So far, this season's biggest problems have primarily been that you can tell when the writers feel pressure, and they speed through stuff that either has logical fallacies, like someone parkour img after being stabbed in the stomach and dumped in filthy water, or disappointing takes on source material, like throwing the Umbers wholly into the Bolton alliance, or dropping any political subtlety to set up an underdog scenario for Winterfell. This season, everything feels a little smaller because people need to be places, and right now!
Which further emphasizes why it's likely the Hound has an important, multi-season role ahead of him. They gave him more screen time than Arya, one if the few definable main characters on the show, to make sure we saw that the Hound is changed. He's still angry, but it's not berserk desperation and bloodlust driving him now; it's righteous fury. The closest thing the Lannisters ever produced to a true knight is moving closer to being an actual application of that trope in the world of Westereos.
They gave him that time to make it clear that from now on, when Sandor kills, it's someone who needs killin'.