Really, I'm just yanking your chain
, but if you want get technical about it, it's a superfluous comma - there's no need for it. This page lays out the rules pretty succinctly:
http://leo.stcloudstate.edu/punct/comma.html
Basically, your sentence "i've yet to meet any exec, who writes his own propaganda" is one single complete statement, thus no need to break it up.
It's the old "Eats, shoots and leaves" thing.