The Swiss news source Blick has revealed that Frijns allegedly turned down two offers to drive for a GP2 team ‘for free’ the 2013 season. He is said to have rejected it because the teams were not frontrunners. Probably Trident is one of the teams. Sauber is not impressed by his attitude.
I don’t know how trustworthy Blick is, but Robin’s attitude strikes me. His rival Bianchi is showing what a big impression one can make with inferior material.