I saw this issued covered on some blogs/news aggregators and was curious as to what the FT reaction would be.
I'm sure the Southwest gate agent's take on things is a lot different than the (highly slanted) blog coverage on consumerist. That said, my rampant speculation is that this was a problem of poverty and not policy. I think it's safe to say that most mileage running FT'ers are NOT scraping together change to get by. People at or below the poverty line simply can't travel frequently (and likely wouldn't have jobs that required them to do so).
The passenger in question was "living on" disability pay. Buying a single ticket was probably a stretch for him. Likely, he did not have the funds to pay for the second seat EVEN THOUGH he was going to get a full refund pursuant to Southwest policy.
For FT'ers, being "forced" to buy the extra ticket with a near 100% chance of a refund is an illusory "cost". It probably is for most travelers, even those who fly SWA. But for the poor -- this is simply not an expense that they can "float".
Again, just rampant speculation on my part.