If someone came to me and told me they were going to bring across underage girls, I would react exactly as this ACORN guy did.
I would try to attain their confidence and attempt to get as much information as possible from them such as dates, locations etc. I would also tell them them where to make the crossing on the Mexican side if I knew he safest place as it's not the safest trip in the world. That of course is IF I thought them serious. I may have just humoured them to get them out of my office if I thought they may be dangerous.
I am not saying that is what happened & I don't know how many ACORN staff these people went to see before finding some that reacted in this way but this is an obviousl setup.
Now - if they'd gone the next step and...