I would hope Korjus is just stepping down for the test to help out his team. Likewise with Yelloly, F.Renault 3.5 seemed to suit him better.
Just looked up Nieto, never personally heard of him. Seems he's been doing the Lat Am F2000 series (F.Renault chassis with VW engine)... no sign of Telmex sponsorship here at least (note the ex F.Renault UK CRS chassis!) -
http://www.latamchallengeseries.com/...lotos&Itemid=5
Curious to see Superstars driver Michela Cerruti on the test entry list for Addax.