In future surveys, this could be corrected for (assuming this is intended to serve as a prisoner's dilemma) by promising to burn the portion of the prize money that is defected away.

Nah, that would just slightly increase the value of the US dollar, and be equivalent to reassigning more money to anyone who's holding any US dollars. You'd have to destroy intrinsically valuable resources instead.

It might just as well be intended to establish how many people are so entrained on "cooperating is virtuous in PD-like problems" that we choose cooperation-like choices without actually thinking through the consequences.

I wonder, now, what a typical audience would select if offered a standard PD problem with the labels swapped.

It seems to me that Yvain keeping money which he himself arranged to give away should not necessarily be considered to have positive utility. That leaves self-interest. But whether self-interest can/should motivate cooperation is the fundamental question of PD in the first place, isn't it?

I don't really see why anyone should prefer giving money to random other survey takers rather than themselves or Yvain.

I'm unable to take the money, but think that there is value toward incentivizing both high survey returns and people taking the monetary prize question seriously, so cooperating was strongly more valuable.