I also thought all radio gear for NVFR must be TSO'ed and so too the GPS if used for Primary Navigation? They could have fitted a certified GPS say a GNS250 or whatever the base certified model is these days, however the base ones are all out of production and the closest is like a 300/400 series and a heck of a lot more expensive. A certified GPS would have done the trick, however wouldn't give the student experience on VOR's in practice and theory, so if they wanted they could still use the non tso'ed Avmap anyway as long as it's not a primary source of nav.
Someone has kindly posted a summary here
http://www.saaa.com/home.php?contentpage=nvfr Will have to find the reg for this, am interested.