"Unlike with other systems, the Linux kernel development process allows turds as well as gems to be entered into mainline"
This would be great marketing tagline for Red Hat. But I hope you realize the flawed logic behind this reasoning. Let's imagine for a second that PaX was a turd, and ExecShield a gem, or viceversa (depending on your touch with reality and experience on security matters and system internals). Why the integration of some of the PaX features was never considered for mainline?
I'm not talking about the segmentation-based approach to NX, which could have understandable drawbacks for inclusion. But, what about the other gazillion advances PaX has implemented a decade ago and everyone has been slowly, but steadily plagiarizing? (yes, you read that right: plagiarizing. The act of copying someone else's work without giving proper credit or obscuring it for one's self promotion).
Further more, "Linux systems are unsafe, or less safe than they need be" implies you mix an objective sense of security with your perceived one. Let's say that the child pornography collection of some pedophile in Thailand does not have the same security impact as the manuals for operating a military beacon. And I agree, but the problem is that Linux is unsafe because of managerial decisions taken by people who don't have the necessary background, understanding and acumen to make them. Just because Linus is a demigod among hippies does not make him a kernel security nutcase.
I won't go into greater depths to demonstrate that your logic is the actual flawed one, besides the seemingly sheer power you have for squeezing a handful ad hominem fallacies in such a short text.
Linux, so good it smells. If you drink the koolaid, it might go away.