No. I understand exactly what the author means. The paper is quite simple and clear. I just think it's a meaningless distinction. Rather than try to create a two tiered decision making process where some decisions should include sunk costs and others shouldn't, you should have a single tiered system that includes social costs.

You don't need to think in sunk cost terms to value plausible deniability. You should view losing credibility with your superiors and peers as a current cost that runs into the future.

If for example you suddenly realize your thesis paper is junk and are faced with decision to push forward or start anew it's not sunk cost to consider that your academic superiors might see this as flailing about and that you should count that as a cost of changing direction. That's just a social cost and not a time or materials cost.