It's not even clear that there is infringement. The GPL merely
requires that people who have been distributed copies of GPL'ed code
must not be restricted from further redistribution of the code. It
does not require that that someone who is distributing it must
available on a public FTP/HTTP server.
If there is something to this (that GRSecurity is somehow in violation
of the GPL), then it would probably be a very good idea for someone
(the community, Red Hat, etc.) to protect the kernel. From my
understanding, at least in America, protections under any license or
contract (especially dealing with copyright and trademark
infringement) are only enforceable as long as the party with the
rights enforce the license/contract/agreement.
There is also something in law called "setting a precedent" and if the
violating of the Linux license agreement is left unchecked, then quite
possibly a precedent could be set to allow an entire upstream kernel
to be co-opted.