Interesting--he's clearly admitting that he believes teachers aren't just there to teach, their job is to "shape" children's minds and futures (leaving just their careers to the teachers would be bad enough). Further, if this article is indicative of "teachers'" quality of reasoning, it hardly makes a compelling case for sending kids to school.
Interestingly, I was home schooled by my parents, who were not only very well-educated (PhD, Cornell, and BS, Cornell) and well-prepared to teach me and my siblings, but also competent enough at some of the other tasks Mr. Arnold describes as "best left to the pros." When I was about 13, my brother and I, with the help of my dad, built an 8x15 foot, two room house (sort of as an extracurricular project), complete with a finished interior, electricity, telephone, and a high-speed internet connection.
So, why would some parents assume they know enough about every academic subject to home-school their children?
Even if what he says is true, most homeschooling parents network with other such parents and usually seek out certain parents who may specialize in a particular subject to teach all the kids in that network.
My wife and I have a six-month old son. We're totally focused and planning on homeschooling him and all other future children. We consider ourselves pretty well educated. She has good general knowledge of most subjects and particular aptitude in art and English, while I specialize in Latin, Gregorian Chant, and Higher Mathematics. We know nothing about manual labor skills, but I'm sure we'll network with people who do and our children will be able to learn how much ever they want about any given subject. (instead of wasting half a year each year reviewing stuff that is already learned and being bored).
Point is, most parents who have done well in high school and college are more than fit to teach their own kids, and kids who are homeschooled develop a better sense of self determination so they can specialize in areas which interest them.
Homeschooling is more relevant to the real world than public school anyway. People work in fields which at least somewhat interest them, and no job is composed of people of one age group. The peer mentality and pressure does more damage to children's socialization than good.