Actually, it's not explicitly untrue. You act as though "made an effort at fact-checking" is an acceptable counter to "didn't fact check". If you are unable to corroborate a claim with at least one other party you have not fact-checked. When TAL was not able to verify some of the more serious claims they should have not gone forward with the story. But don't take my word for it, even Ira Glass agrees (emphasis mine):
I can say now in retrospect that when Mike Daisey wouldn't give us contact information
for his interpreter we should've killed the story rather than run it. We never should've
broadcast this story without talking to that woman
So, they didn't fact check his story. They admit to not fact-checking his story. And it wasn't hard to find the interpreter. In fact the Marketplace correspondent, Rob Schmitz, claims that he found her on his very first Google search. I absolutely love This American Life, and so it saddens me to see them screw up like this. But they screwed up. Badly.