"In all, so-called "Red Teams" of Homeland Security agents posing as passengers were able get weapons past TSA agents in 67 out of 70 tests — a 95 percent failure rate, according to agency officials."
They're not mutually exclusive things. Red-teamers often have quite a bit of expertise and are smarter than your average threat. And the point of these exercises is precisely to continually improve in response to the findings. But alas, most of the people who bring guns on to planes aren't threats anyway (at least not in the typical sense), they're idiots who forgot their CCW in their bag.
Well funded and planned security threats are overwhelmingly outliers. Most security threats in airports are drunk and pissed off idiots, and most terrorists are lone wolf crazies with zero experience or expertise in security.
Those aren't the ones who are actually going to do serious damage. Drunk pissed off idiots haven't planned to be carrying anything anyway. Lone wolf crazies might get organized enough to be in the line in the first place... and if they do, well, crazy is not actually mutually exclusive with smart or even knowledgeable. And you still have the assumption that it matters how smart you are. There are only so many places to hide a weapon, and being smarter doesn't give you more choices.
A red teamer is going to be better suited at picking the right thing to hide and right way to conceal it, not because they have more options, but because they understand which combination of options are more likely to exploit the weaknesses of their target.