For another example, just because the GPL is a work of copyright law doesn't mean its goal is not to abolish copyright law. The professor knows that the more students he influences toward anti-consumerism, the closer he'll get to living in a socialist world where he can sit around and read philosophy all day. Or maybe he won't need to; philosophers are really only needed to answer existential questions and problems--if they managed somehow to perfect the world, their job would be "done", similar to a doctor in a world where no one falls ill.
Note that this has nothing to do with my own opinions. I like advertisements, strangely enough; I find they make television and radio feel "connected" to reality, in a temporal sense, in a way that just downloading old TV series and podcasts don't. It's the difference between an airlock and an open window; I feel "stuffy"--out of sync with the world--when I don't hear anyone telling me what brand of laundry detergent I should be robotically consuming.
This professor was too naive to realize that these evil corporations he so despised were the ones paying his salary, giving him the opportunity to sit around and read philosophy all day.
All the students just thought he was weird and pretentious.
Instead of sheltering your kid, why don't you teach him how the world works instead? Educate him to make his own judgments when it comes to marketing and advertising.