You're quite right about the above.
But there is one scenario that I can still imagine, where the student requested the presence of the iPad as a secondary device to verify his position against his primary VFR navigation attempts. It's not illegal to have such secondary device on board and an unsuspecting/inexperienced instructor might have initially allowed this as a supposedly "harmless" temporary aid (without the school / chief pilot actually knowing). Things went wrong when the student got accustomed to the devices and with the gradually lowered navigational support from his instructor, he grew too dependent on the iPad instead, which is an obvious dead-end street. I bet the previous instructor realized this and tried to talk him out of this habit, but the student didn't want to "give up" the "illusionary" progress he made! That's why he became very stubborn with the previous instructor, who in turn, handed the student over to the OP.
Either way, the solution is in the hands of the student. He must let the iPad go from the cockpit, and this is the OP's problem.
The student can either swallow the cost of the dead-end street excursion in training, or sue the flight school and the previous instructor to get the money back. (Or agree on lower fees for a few additional hours - this would be the best for the above scenario. ) but, this is NOT the OP's problem.