I've performed comedy in both cities. And there is definitely a cultural difference. Melbournians do take their comedy a lot more seriously. They are also quirkier, I think, and can be more experimental. Melbourne is easily the nation's most left-wing city, and so the comedy does tend to be more politically correct.
Sydneysiders are more brash, brazen and even ostentatious. (It's no surprise that Austen Tayshus himself hails from there.) The comics are also less PC, though still left-leaning. And they do tend to do material that would receive appalled gasps down in Melbourne.
Also, I think Sydneysiders generally aren't as interested in the medium. So, the fact that this event was cancelled doesn't really surprise me.