He did provide PE ratios for competitors as well, and HP is the largest PC maker. He isn't valuing them the same as Apple, just that the PE ratio should be similar.
The line of reasoning applied here escapes me. In what way are the hardware and consulting business lines distractions to one another? It's like saying a car company's manufacturing business is going to get distracted by the company racing team, because it's possible to draw up different P/E ratios for the two. This overlooks the fundamental and inextricably interlinked business relationships between the two. And it casts aside all kinds of follow-on benefits, such as market & mind share, the halo effect, cross-pollination of new business ideas and seeding of innovation.