Although legally you may be right, I'm pretty sure that during IMC *training*, the instructor would not appreciate you pulling out the iPad (or any portable device for that matter) and use that as your primary nagivation device. Or secondary/backup device for that matter.
That's true but that is nothing to do with the GPS
It is what you get with an old fart of an instructor. A modern instructor will train you in the use of modern methods, to the maximum extent permitted. Same in the PPL syllabus; only 1 or 2 specific exercises in the whole PPL have to be non-GPS.