Low reps are for size and high reps are for cutting , I hope this helps .
It doesn't.
For one thing, low reps are for strength.
Secondly, it's the heart rate and caloric deficit that you're targeting, not a rep scheme - you could use either. High reps just easier to get heart rate going. It really depends on what you're eating and what you want to be capable of after the cutting. Isn't there research saying that going hell for leather, high heart rate isn't as efficient for fat burning?
Another consideration is that your body will obviously adapt to the rep scheme you use during the cutting which means if you want to keep your strength as much as possible, you might be better off keeping the reps low.
As for Phil - I think bodybuilding is a pretty boring way to train (but each to their own) but I don't really see the point of him going all out on heavy weight when he is cutting. Phil is in it for the money and status. Nobody does quarter reps on leg press for "fun", that's for sure.