Actually, copperhead itself is sort of loosely following grsec's model, which is rather unfortunate. Their licences, where required will be GPL or compatible with upstream, but otherwise copperheadOS itself is not FOSS. I kind of get that it's hard to make money in such projects, but I really don't see how this strategy works for them, unless the goal is just to be bought out by someone.

Thanks for the link. Happy to hear they're maintaining Linux-hardened themselves.