"According to the TSA document that Mo'M cited, disposable lighters are acceptable in checked luggage ... "
Actually, according to that document, NO lighters are allowed in checked baggage, only in carry-on. I think the bottom line is they don't want any type of either ignition source or accelerant in the baggage compartment. Fires (and subsequent crashes) have happened before.
I will agree that they're not perfect (consistent), hence boofa's butane being left in his bag. Personally, I think it's all a pain the the a$$ --- but face it, if it weren't for TSA folks and their admittedly annoying and sometimes inconsistent security checks, none of us would be flying. Man, I'd really hate driving to Vegas from AL.