Difficult one and I'm not familiar with the workshop environment.

I can see cases to illustrate variations in style or tune where the purpose is hopefully understood and explained but outside that, generally speaking, it is IMO the height of ignorance to re-play what someone else has done.

I wasn't there to judge but the "famous fiddler" could have easily lost every bit of respect I had for him/her if such an action was taken without good (educational) reason.

Jon