The post is basically a bunch of quotes about Apple a netbooks. Some saying they should have one because an Apple netbook would be cool (it probably would be), some saying not having a netbook is hurting Apple (they seem to be doing just fine), some making shoddy predictions about slumping sales, and some saying Apple is a missing an opportunity (maybe they are).
And Gruber's conclusion appears to be that had Apple had a netbook they'd be losing money. How does one reach that conclusion? Presumably, he means that netbook sales would cannibalize high end laptop sales. But that's doubtful. Most people who buy a netbook either have a high end laptop as well (like me -- I have a Macbook, a Sony VAIO, and an Asus EeePC) or were never going to buy a high end laptop in the first place.
So... you can debate the merits or necessity of Apple adding a netbook all you want, but claiming that adding a netbook would have caused Apple to _lose_ money is just silly.
That said, Gruber appears to be a Yankees fan, so he can't be all bad...