These days, the reasons to use Linux instead of Windows is so overwhelming.
The code for SELinux that's in both GNU/Linux distributions and Android are all open source, and anybody can go and review the code or change it.
The existence of Linux on the desktop doesn't remove the threat of having NSA code built into your processor, but if you honestly believe SELinux is a backdoor then feel free to point out where in the source code the backdoor is located instead of spreading FUD for no reason. SELinux has nothing to do with what the article is talking about, that is, having malicious firmware baked into the processor at the hardware level.
That's tangential, though. More importantly, I expect NSA contributions to be poured over because the NSA isn't highly trusted, and it would make a great mailing list post to say "The NSA has a backdoor in our code here, here, and here."
Many eyes and a suspect contributor make all backdoors shallow.
They wouldn't need to purposely sabotage the linux kernel anyways it's like 15+ million lines of code they can easily review and find bugs as a homework assignment in first year internal classes on offensive exploitation.
Let's say they indeed decided to include something in the code submitted. It's an open source project, and it is a just matter of when someone will catch that. Once someone catch that, it gives them nothing but material evidence that they are up for something there. (and for that matter, it's not that every Linux users will have SELinux enabled to begin with.)
IMNO, hardware backdoor on the processors is a bit skeptical, though. I'm no expert on this but I don't know how easy to even exploit this type of backdoor without an assistance from the OS kernel. (Which MS might have implemented somehow.)
It's really a no-brainer to make such breakpoints that watch data in memory or registers that will be triggered by (e.g.) just processing a specific DNS packet.