I'm not sure that your claim about where the line is holds up: the GPLv2 never requires you to give your source to anyone unless you first give them binaries. That's why web sites don't have to give out their sources to everyone who visits their site if they use a GPL library for instance.

In any case, if what you say is correct, the grsecurity team are still trying to hold the threat of a more annoying experience over their users in order up prevent them from exercising their rights under the GPLv2.