Did you find a resolution to this? I'm having the same problem.
+1, the whole python thing is a mess on osx/homebrew. I ended up braking my python installation entirely it seems when trying to get pyqt4 working. Now I don't even have pip and homebrew can't seem to fix it.
I ended up using a windows machine.
I managed to make it work forcing install of PyQT4 using: brew install cartr/qt4/pyqt (as seen in: https://robonobodojo.wordpress.com/2017/02/08/installing-pyqt4-on-mac-osx/) As well as installing some extra libs using pip that are not listed in the docs, like svg.path, but those you can pick from the errors. Finally form the cloned git folder just run ./flatcam