I just know this guy was like "Damn...it's time for my break and I'm gonna go sit on the crapper and have me a cigarette..."
It's not his fault he doesn't know about methane gas buildup, right? The story says "the man was not severely injured and drove himself to Clay-Battelle Community Health Center." I guess that depends on your characterization of "seriously injured." Almost blowing yourself up in a Port-a-Potty has gotta be a pretty severe blow to the ego. I'm just saying.