I realized this guy was a dumbass when I read number 1. I am a Redhat Certified Engineer, and I have several close friends and co-workers that are Linux Administrators for DoD, ORNL, and Y-12 (All in Tennessee). Here is a reason why every single freaking one of these institutions rely on LINUX (mostly RHEL) for the utmost security. The OP has obviously no idea what SELinux is or just how actually secure it is. Its a shame there are so many self declared "security experts" involved with Bitcoin. I am no expert, but I do know my ass from a hole in the ground.
Warning. Total derail attempt. Warning.
Do the RCE exams still have a in-class practical portion? I just finished the LPIC-1 - could have done it in my sleep.
Also do you or your peers have a lot of interactions with auditors on the system security side? I keep finding places where inappropriate security policies (like 90 day password cycling) are being enforced not by admins but by auditors because said policy made it into someones best practices book.