You’re wrong. An item might be pertinent to an investigation - an eyewitness for example, even if when interviewed they couldn’t provide useful evidence.
Did you read the part that says it was the investigative team informed him material was present that is pertinent? IOW, the investigative team HAS LOOKED at the material.
This isn't material found in a particular place or at a particular time whose mere presence indicates applicability. The emails have been read, and consequently the investigation has been reopened. Were it otherwise, Comey has just thrown his career in the toilet.