I will note that he seems to shrug, especially in footnote 19, as if to confess that whether lobsters feel pain or merely express reflexes is basically unknowable, not for any lack of humans trying to figure it out.
He seems genuinely conflicted, rather than firmly opinionated, certain only that people should take these questions more seriously. Or maybe he's being coy, to avoid alienating the gourmand.
I'm curious if he hesitates to kill spiders since writing this article. Spiders are similar to lobsters. Spiders exhibit preferences. Maybe we should all hesitate to kill them. Or maybe that's just crazy. I don't know.
Incidentally, if you want to feel incredibly confused about how you balance empathy towards human and nonhuman things, including arthropods, (and robots, and sociopaths, ...) you should read Do Androids Dream of Electric Sheep. It's a short novella, it's culturally relevant, it isn't really captured by the films, and it artfully messes with your head.
DFW on lobsters: http://www.columbia.edu/~col8/lobsterarticle.pdf
(The PKD is pretty easy to find, no link.)