I've tried running the grsec kernel on Arch a few times, and I've never gotten it to boot once, it usually just panics immediately. In the same way openSSL was a base of nobody wanting to invest in covering your own ass, there is no interest in having a legitimately secure kernel the way grsec proposes, and even in Arch there are only a few people working on it and while it is in the official repos it really should be in the stock kernel if they wanted to send a message.