Someone above touched on this - my exact thoughts as I was watching as well. The guy made it seem way too easy and both Mike and Gus thought immediately that this meant he wasn't thorough, careful, thoughtful, etc.. enough and therefore was probably prone to mistakes.

German dude gave them a step by step run through of how it *could* be done but made it seem like a nearly impossible task. Yet he gave them all the steps it would take to get the job done if done properly. A thorough explanation. They felt more comfortable knowing the dude understood the enormity of the task but still thought it possible to complete so long as they gave proper considerations to all the risks involved.