(Hardin is also famous for his work on "the tragedy of the commons." For a response to that see here (short version: empirical research shows that commons can and do work rather well). If commons cannot work it is odd that they survived so long, and died not a natural death from their own failures but a very artificial one motivated by greed. That tragedy is described by John Clare in two poems here.)
Argument by ridicule is an interesting kind of argument, because one can always humorlessly bite the bullet (and claim that one is heroic for doing so), but also because nothing in particular follows except the rejection of the ridiculous view. It doesn't tell us what to do or think instead (nor, presumably, would the kind of philosophy consisting only of jokes that Wittgenstein imagined). It is like arguments based on due respect for the miraculous. We enter the territory of the vague and the subjective, which I mentioned here. I think this is, at least often, where ethics belongs, but it is a difficult area to navigate. The temptation always seems to be to flatten the map and scrape the creases out, to escape to a flat world, however ridiculous, however evil, it might be. Harrett Gardin does us a great favor in showing up Hardin's shortcomings. It's a shame his paper isn't nearly as well known as Hardin's.