Utter claptrap.
1. I cannot imagine why anyone would think that the Free Software Foundation would ever sign anything to assist in the production of proprietary software. Signing an affidavit always exposes one to risk; why would they assume risk to assist a software hoarder?
2. The GNU/Linux thing has been argued and argued and while I once fell in the author's camp I now realise that the FSF had it right all along. It was when I heard someone refer to Cygwin or macOS as 'Linux' that I understood that people really do confuse the GNU operating system with the Linux kernel. Since then, I have tried to be careful to refer to it as GNU/Linux.
3. The GPL does a better job of achieving the FSF's goals than the LGPL; it is appropriate for the FSF to recommend it.
Who is this JOTTINGE guy?
