(Spyder dev here) This is not our fault nor Enthought's one, but PySide's: the Python Qt bindings distributed by Enthought. Unfortunately they are not very stable (causing crashes like the one you described) and currently unmaintained, so we can't do anything about it.
Our recommended installation method on Mac is using our DMG (which uses PyQt4, a more stable set of bindings) and then switch your interpreter to the EPD's one. Or use MacPorts, if you feel brave enough :-)