I'd only entertain the possibility that it was tongue-in-cheek if it came from someone critical of the World Bank and laissez-faire economics in general, for instance Joseph Stiglitz, who has also been chief economist at the World Bank and was critical of it. But if you're fine with structural adjustment – which many see as basically tear-down-orphanage-to-build-mall – you don't get to make that kind of jokes. It's too close to home.
If it had been tongue in cheek or satire, that would suggest he also had enough capacity for introspection and empathy to see what is wrong with it. Looking at both his career and personal life suggests that he does not.
I mean this is presumably why it wasn't a publicly published memo or policy recommendation. If structural adjustment and economy management is part your job, you might have some steam to let off about it in private, and plenty of draft ideas and documents that need refinement. It does become a mistake when it's made public, but that doesn't mean it wasn't a joke originally.
