What a great idea, to test self-confidence in extremely nervous circumstances. What could even go wrong.
If an interviewer makes some crazy assertion, then I pretty much flip into the mode of "how do I get out of this interview ASAP, as there is no way I'm working with this idiot". Whereas in the office, I'm the guy that sends the really difficult mass email that calls out his boss, if it is really needed. Engineering is not interviewing, and vice versa; why would you expect identical behaviors in both?
And yup, I am self selecting out of the situation where the interviewer is not an idiot and just 'testing' me. I'm fine with that, because I'm also selecting out of a job where people aren't willing to treat me with respect.
Interviewing is largely voodoo; we shouldn't be inflicting cognitive pain on people based on our random selection process. The only measure that has ever been shown to be predictive is past performance. So let's talk about my past performance, and leave this amateur hour psychological testing in the trash bin where it belongs.
Don't try something because you sit down and think "hey, I am going to create an artificial situation, and then guess at what a good candidate would do[1]." Then see if he does that.
[1] Which is often "what I (imagine I) would do."
Or maybe that's just me; nervousity in presentations or interviews or even talking is IMHO an indication of not knowing what you're talking about. And knowledge is confidence.
I've interviewed a number of people who were incredibly confident in their language, voice and body language who clearly had no idea what they were talking about.
Similarly, I've interviewed people who clearly knew way more about the subject matter of the job than I did but who were incredibly nervous during the interview either because they were intimidated by the idea of working outside of academia, real/preceived language limitations, or because they were just incredibly shy and awkward.
I've generally tried to look for people who fit the sweet spot in-between: confident and sociable enough to be reasonably comfortable during the interview and humble enough to not be brash. The more "customer/client" facing the position, the more I care about the confident and sociable part.