Has anybody considered looking into getting a developer to try and do a WineBottler/WineSkin port of it? A lot of software is now ported to Mac with a straight-up WINE wrapper, including FL Studio and ClickTeam Fusion 2.5 (Construct 2's rival software), and some Steam games including System Shock 2. The deal is, the 'developer' of the port creates a WINE wrapper, which wraps the software in a Windows emulator, and then they proceed to modify the wrapper (and sometimes the software itself) to work out any and all bugs which occur due to the emulation.
It's a pretty quick and easy way to port. You don't get some of the benefits of OSX's multitasking (i.e. the whole thing would run in one Window like it does on Windows, you couldn't separate the toolbars and such over the desktop like a lot of Mac stuff does) but it'd be completely plausible. If there's enough of us who want to get Construct 2 on Mac, perhaps we could talk Scirra into doing a WINE Wrapper port themselves, since they have the source to C2 and thus they can make changes to the base software for any issues that may come up due to the emulation.