Correct me if I am wrong here, but it sounds like GNU project requires that either all code is assigned to FSF, or none and then the project need to enforce copyright themselves. In this case, the current maintainer want to assign copyright, the new co-mainter don't, and thus the project got an internal conflict between the maintainer and co-maintainer. The hostility is thus primarily between the two maintainers, rather than between GNU and Benno.