Turn it into Funhouse.
During the day it's a queer kids creche, during the night a gay play den. They can get around licensing laws by holding a tombola - tickets are £3, all prizes are a can of booze. You just don't get to choose what you're drinking (not that it ever made any difference)
Open at Cafe.
Ideally, with some kind of burger/hotdog/milkshake theme. Of course, you'd need to open at 2am - giving you the necessary hour and half cleaning time. The milkshakes will have whiskey in.
(Re)open the sex dungeon.
I wrote an article on The Joiners four years ago, and one of the things I was told (though I can't for the life of me remember who it was) is there used to be a sex club/dark room/dungeon in the venue many moons ago, in an upstairs bit. There also used to be a roof terrace. Far as I know, there are no competing gay sex clubs in Hackney, they'd have a captive audience, and one that wouldn't mind the lights up and awkward shuffle home to their wives around midnight.
Turn it into an art instillation.
Get some massive art gallery/artist/fashion brand to buy the whole thing, and run it as an interactive piece of art. Equip the barstaff with Equity cards and turn the Karaoke into performance art.
Or you can just write a letter and tell the licensing people how ridiculous they're being: London Borough of Tower Hamlets, Licensing Section, 6th Floor Mulberry Place, 5 Clove Crescent, London, E14 2BG.