I agree with Kevin. Although sometimes CP is wildly inconsistent with enforcement of their own rules, I've never heard of someone getting fired for one instance of "letting someone get too close to the ride." Heck, on Magnum, you are probably hiding behind a pillar so what could you do to stop it anyway? 
Miss a seatbelt or lapbar, you're going to generally get written up and this can happen up to three times (verbal, written, and final warnings) Termination is the fourth. There is a such thing as a two step write up where you get two or more of these steps at once, but I've never seen anyone get fired for one incident like you describe. Maybe you'd get fired for clearing a train with guest on the inside of the gates at Wicked Twister, but is anyone seriously dumb enough to allow that?
There's something more to this story...
-Matt
2001 Magnum Crew
2003 Magnum Crew
2004 Magnum ATL