Certify the software, not the person.
I don't think you're considering how everything works together - in mechanical engineering a certified engineer designs her machinery around other tools that themselves were designed by certified engineers, all using manufacturing processes designed by process and industrial design engineers.
What you're claiming is equivalent to a technical engineer designing something based on equipment designed by - for all intents and purposes - a random person on the internet, and you're now responsible for determining all the mechanical qualities of everything yourself.
I think you're dismissing what it means to say "I am a professional engineer and I approve of the use of linux" in such a context. The only rational approach is to only take OSs (or any other part of your software stack) that has itself been written entirely by certified engineers.