This could be a real enhancement to MuseScore: I believe that a lot of people would start to develop plugins because it's so easy with Python. (At least one python plugin developer would be there for sure: Me.)
The implementation of such a Python binding could be made in two different ways:
One just implement it in C(++) with the Python C-API.
I would really love to have python plugins in MuseScore and would develop a lot of them!