How do you enforce it? What if one day you discover FEM doesn't fulfill it anymore? Do you catch all the issues during review? What if you miss an issue? What if you need to change the code which is not a part of FEM? Aren't you annoyed it doesn't fulfill the coding style you've used to?
As far as I can see, flake8 is disabled:
https://github.com/FreeCAD/FreeCAD/blob ... #L124-L130
Do you mean you run it yourself each time you do a pull? How is it being run and when?