1. How often do you go to another mac with your flash drive, needing to run Bitcoin? Generally I don't think portable apps have any point on platforms other than windows.
2. It's written in AutoIt3, so it can't be used naivelly on Mac or Linux.
3. I don't have any Apple product and neither do I intent to buy one
so I can't even test it.
I suppose that a bash script wrapper for Linux could work on mac too but we are talking about making it from scratch in another language which I also dislike (Bash scripts)... The code is open though so if someone wants to convert it somehow. I know that for Linux a similar language to AutoIt3 is AutoHotkey which works both on Linux and Windows, don't know about Mac though.