Mistake in Karp's paper on NP-Complete problems?
To cite the blog post: 


  For arguments sake, lets say that in Karp's classic paper Reducibility Among Combinatorial Problems, where he proves 21 problems NP-compete, he made a mistake on 0-1 programming.


That is, the blog author does not state that there is a mistake. It is just a gedankenexperiment.

That is, of course, not to say that there is none.