Unless I'm mistaken, Bodhi's dad drives a BMW. Which is rear wheel drive.
So its not surprising that new tyres are recommended to go on the back, as the driven wheels are more likely to break traction - the chassis dynamics of a BMW dictate oversteer, not understeer.
As a front wheel drive car, your GTi is going to understeer long before it oversteers, unless you drive specifically to provoke it.
Its even more important on a front wheel drive car, where not only are the front wheels transmitting the driving force, but are also trying to steer the car.
The fear is that if a front wheel car has too little grip to the rear, you will unwittingly create a fwd car that will easily oversteer, but to be perfectly honest if the tyres on the back of your car are so bad where you'll get oversteer during normal driving, you should be buying four tyres, not two!