Ah, I loved this. When we were all thinking "Snape_after_DH" I thought Aberforth, FTW! He'd have known Snape for years, and a bartender -- especially one who just happens to be Albus's brother, and not necessarily on good terms -- is exactly the person a spy would know.
The "wabi-sabi" appreciation for the broken, the bitterly brought up, the ones who are carelessly treated by a golden Gryffindor, are again exactly IC for the owner of a rural pub. Aberforth knows how to deal, as Snape eventually does, too. (I wonder how much of that pragmatism and competence Severus learned from Aberforth? And I wonder what House Aberforth was in?)
The magical extension of the concept of scapegoating is very creative, and fills that canon hole about the goats perfectly.