They're going to want to read Fred Cohen's "Computer Viruses - Theory and Experiments" (http://all.net/books/virus/index.html) and maybe some of his other papers, first. After understanding that paper, they might want to lower the bar a bit.
Security through obscurity will not solve their (or anyone's) problems.
Also, someone claiming a system to be "cyber attack proof" is clearly misguided.
Isn't that what the NSA tried with SELinux?
SELinux is a good thing, but it isn't attack-proof, and I doubt anything can be.