So sue them and a court opinion can demonstrate where the line is and how much code can be replicated before attribution is required (and the product can be refined to ensure compliance).
They could push boundaries and publish one trained on all of Microsofts internal source code. Would for me be a great demonstration that they believe the "it's fair use and not violating copyright on the training data" argument.
It's more likely they'd sue someone who used it to develop something that ate into their lunch by saying it infringed on one of their 'secret' Linux patents they sabre rattle about every now and then.
The product is already dead. It's not just Microsoft that would be violating the license but any company using the application and Microsoft can't shield them.
Innovation should push boundaries.