I'd dob the instructor in to the CP. What a joke. Sims (every one I've been in)cannot be used like the aircraft to do visual circling without some latitude for sim errors/limitations. It is a VISUAL manoeuvre. Here, the runway threshold MUST be kept in sight at all times, which you can't do in the sim, quite apart from the degraded sim visuals, which are at the best like flying in pouring rain in the dead of night.
Sounds like an FMS nerd if he's requiring use of fixes/magenta lines just to do a base turn. Doesn't work for #$%^ does he? They seem to be hell-bent on using the box...