I don't think he was naive. Philosophers think quite a bit about what it means to create for yourself a bubble of X in a larger sphere of anti-X: living a meaningful life when life is finite and all memory of you will be eventually erased, for example. Just because death allowed for the natural selection that evolved humanity doesn't mean that you can't be against it. Just because corporations created the opportunity for him to thrive, doesn't mean he can't speak out against them.

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.