I do business on cragslist daily, so Im very familiar with the site and how it operates, as well as the buyers. And if Ive learned anything for this marketplace, and Elway for that matter, its you have to have a plan B.
Id suggest selling the tickets in an unpopulated area for this situation. Meet in the woods or on top of a mountain. Then build a trap, maybe a giant hole in the ground, covered by leaves. If you get any sense at all that the buyer is a chiefs fan, lure them into the hole. Once it's in the hole, take off your ****, and sexually/violently rub the tickets on your nipples as a display of dominace, then leave. This not only punishes unsuspecting chief fans for being flat out liars, it stikes fear in their wife/children as well. Good luck.