And if it isn't, as I conclude (after an introduction discussing the difference between being valid in a simplified artificial model and the real world!), then it's perfectly legitimate to ask whether accusations of sunk cost fallacy - which are endemic and received wisdom - are themselves fallacious.
But none of this changes the fact that the title is still misleading. Even if accusations of sunk cost fallacy are themselves often fallacious, this doesn't change the fact that you are arguing that the sunk cost fallacy is a mode of reasoning which doesn't often occur, rather than one that is actually valid. Claiming that it is not serious may indeed be overturning a basic principle, but it is not the basic principle the title claims you may be overturning. Sensationalize if you like, but there's no need to be unclear.
Even if accusations of sunk cost fallacy are themselves often fallacious, this doesn't change the fact that you are arguing that the sunk cost fallacy is a mode of reasoning which doesn't often occur, rather than one that is actually valid.
I don't know how you got that from the essay. To quote, with added emphasis:
...We can and must do the same thing in economics. In simple models, sunk cost is clearly a valid fallacy to be avoided. But is the real world compliant enough to make the fallacy sound? Notice the assumptions we had to make: we wish away issue
I just finished the first draft of my essay, "Are Sunk Costs Fallacies?"; there is still material I need to go through, but the bulk of the material is now there. The formatting is too gnarly to post here, so I ask everyone's forgiveness in clicking through.
To summarize:
(If any of that seems unlikely or absurd to you, click through. I've worked very hard to provide multiple citations where possible, and fulltext for practically everything.)
I started this a while ago; but Luke/SIAI paid for much of the work, and that motivation plus academic library access made this essay more comprehensive than it would have been and finished months in advance.