I hate to think of how many job interviews I've had. Doing contract work has often meant that I don't meet my interviewer face to face until I show up for work. In fact, I've participated in a number of successful interviews while flat on my back in bed.
Interviewers have been a mixed lot too. Usually it's one-on-one, but occasionally there are multiple interviewers, and on a speakerphone to boot.
I'm used to these things by now, but some people have a hard time relaxing under such conditions. In terms of stress, it ranks up there with speechmaking.
If you've looked at books about making speeches, they have a number of hints for helping you to relax. One famous book suggested visualizing your audience naked.
And then there's this one: Dancing Naked: Breaking Through the Emotional Limits That Keep You from the Job You Want.
So maybe this guy was only trying to help.