The problem with this is the unanswerable question:
How do you define a Professional System Administrator?
Unlike professionally licensed fields (architects, engineers, lawyers, doctors) there really isn't a unified (or even fractured) system for licensing / credentialing sysadmins (though arguably the profession would be well served by one given some of the people that pass for "sysadmins").
Similarly membership in a professional organization isn't a prerequisite -- even LOPSA (arguably the largest "sysadmin association") doesn't cover more than a tiny fraction of our active contributing membership.
Aside from the above, I think the idea of exclusionary membership runs counter to the principles underlying Stack Exchange -- Even though Server Fault is an oddity in that we're geared toward being a site "for professionals" the idea of open membership and a community-controlled meritocracy seems like a better fit than restricting who can say what.
Sometimes the best ideas come from the outside, and the community (SF and System Administration at large) should not be set up in a way that excludes outside voices. Better to hear them and then decide if they're crazy or not.