Re: "as fast as the fastest PCs."
Relax, we don't know the context of the "as fast as the fastest PC" quote - the exec might have describing the speed of performing a particular quick task in Photoshop or iMovie or something. Desktop CPUs haven't been getting much faster at single thread tasks in recent years anyway - because they've been fast enough, focus has been on improving energy efficiency and or just adding more cores.
What Apple actually displayed as a bullet point was 'Faster then 92% of the notebook computers available last year" which Anandtech find very plausible:
Apple mentioned during the keynote that the new A12X is more powerful than 92% of the available laptops in the market, which isn’t very surprising given the performance levels we saw on the A12.