That really surprised me! One of those two scripts was the first season "Shore Leave," which I thought was an entertaining light episode, at least as good as "The Trouble with Tribbles," the best-known comedic episode. The other was the first episode of the second season, "Amok Time," which did more than any other episode to define Vulcan culture. It seems to me to be a perfect example of Sturgeon's motto "Ask the next question" applied to Vulcan claims to logic. C and I have rewatched the first two seasons of Star Trek on Amazon Prime, and we both found those episodes among the best.
Overall, I find Blish an intelligent critic, even if I disagree with him. But I'm really unable to imagine what he finds so deeply flawed in these episodes.