I don't know why this gets debated all the time. You play for SAFC you live in Durham! Manchester is a dump, so you play for MUFC you live in Cheshire. Simple.
Back to the OP, Short won't cash in because he knows we're a good bet in the long run. We get into Europe and he's got a cash cow. He's got to spend it to get it back, but he knows that already, being a billionaire and all.
Mind you, you know the old gag: "how do you make small fortune from football? Start with a big one and buy a football club"!