i think the simple explanation is that this line doesn't take place on Circe's islandThat line from the Canto XXXIX did strike me as strange as, although there were obviously lions on Circe's island, I was picturing a smaller domesticated or stray cat. (and the canto project notes avoid explaining it)
it's the same contempt any tenant feels for a landlord or any other parasite that leeches off himThe contempt that comes into his voice when he starts talking about usury and stuff is still there from the earlier cantos - "local loan lice"