Can I write tests for c# sealed class with protected methods using robotframwork?

I can't modify the original class. if i pass the class name to the python Ctor i get: "TypeError: cannot derive from MyClass because it is sealed". and if I don't pass it as Ctor argument and use its methods directly i get: "TypeError: cannot access protected member ExecuteTest without a python subclass of MyClass"

to be clear, I'm testing with IronPython and robot framework. and tests are for c# classes.