Those of us who have our thighs caressed by a high school graduate every time we pass through Missoula International Airport* often wonder about the theoretical limit at which TSA screening procedures would not be worth preventing terrorist attacks. I call it the Castillo Limit, after former Miss USA Susie Castillo, and it’s hard to say where it would lie. Taking my nail clippers does not approach the Castillo Limit. Making everyone fly naked in a tank of that breathable gelatin from The Abyss seems like we overshot it. Somewhere in the middle is the precise border between liberty and security, but where exactly is a matter for our elected minders and, of course, international terrorists. At least one and possibly both groups got a little closer to discovering the Castillo Limit yesterday, when the Times announced that terrorists were exploring the idea of surgically implanted bombs.