It’s a story as old as time. Somebody ignorantly bashes Linux on the basis of ridiculous misconceptions, then the Linux dude responds, and he’s such a complete dick you find yourself wanting to go buy a dozen copies of Microsoft Office just to spite him.
UPDATE: Shocked at the reaction the rant on his (formerly) obscure blog has generated, and having learned a lot actually talking to the teacher in question, the dude issues a sincere and thorough apology and a retraction of all the more clueless things he said. Kudos to him! Good man.