The company probably would not have paid $18k if he did not put in the 7 weeks of work...

I think the point of the post is that he _didn't_ do 7 weeks of work; he did 7 weeks of mostly not work.

But look, they occupied his time for 7 weeks full-time. He could have taken another project (opportunity cost) if not for this project. I mean, the inefficiencies of their business processes are not his point of concern - they occupied his time and they should pay for it.