The GNU GPL Licence is not an GNU Library GPL Licence.
You can check the licence file at the top of the linux tree. The only linux exception to the GNU GPL is for "normal" programs (no hardware driver code) above the syscalls.
That story about GPL symbols does not allow to distribute close source modules. The fact is the main coders not suing those distributors, in respect of Linus T. choice:
he prefer to tolerate a close source module driving a piece of hardware than nothing. Many disagree, but nvidia can be glad to be that lucky.
Moreover, this tolerance can vanish one day...
AFAIC, I do not want a close source program driving my hardware.
Better choose a GPU whose manufacturer is way more open source friendly