Did they know what he would pick, or did they know they could have feigned some computer error in case Arno made the wrong choice and made it seem like he picke

Did they know what he would pick, or did they know they could have feigned some computer error in case Arno made the wrong choice and made it seem like he picked Penn & Teller straight away in post? The "magician's choice" wasn't a psychological trick like what you're suggesting. Penn & Teller were the only real people of the choices given.