I find that highly unlikely, especially considering that there's no reason to tune a car to run spring pressure.. you can just plumb the vacuum line on the wastegate directly to the nipple on the compressor outlet and it will run wastegate pressure, no tuning needed. It's far more likely that the car was having serious issues which put it into limp mode, making it run wastegate pressure.. so he decided to make it someone else's problem rather than trying to fix it.
I would take the car to a reputable Subaru shop with a tuner and have it looked over.. I'm willing to bet there's no tune on it at all. Hopefully nothing is damaged beyond repair.