Melbourne?
No, it's a joke playing off how Melbourne fans (at least some) don't want to look like Sydney, per:
They're not as fussed about it being similar to MCFC's (although that's not to say that they don't mind). Far more pressing of a point for them is that sky blue is the traditional "sporting colours" of the state of New South Wales, which is why Sydney FC play in sky blue already.
Plus is I looked up the Sydney kit after reading that and as light blue kits go I kind of like it..