>>522
Bisonの問題はこういうことで、論点がちがうだろう：

We didn’t change the terms because of sympathy for people who want to make
software proprietary. Software should be free. But we concluded that limiting
Bison’s use to free software was doing little to encourage people to make
other software free. So we decided to make the practical conditions for using
Bison match the practical conditions for using the other GNU tools.

http://www.gnu.org/software/bison/manual/html_node/Conditions.html