Using code signing on OS X sounds like a good idea but does require careful analysis to ensure it is being used correctly.  However, in your example, you are using and signing the Apple-supplied system Python.  It is not advisable to modify system resources like that.  You should open an issue with Apple to request the system Pythons be signed (https://bugreport.apple.com/).  I'll keep this issue open for further investigation of signing of Pythons supplied by python.org installers for OS X.