My guess - and this is only a guess - is that the "telephone cord" was placed there to secure the knife in the weightlessness of space and during what NASA thought would be a rough ride.

Grissom had only a 15 minute flight and it was entirely over water. He was up and down like he was on a giant roller coaster ride. Plus, this was only the second manned space flight in U.S. history. NASA still had a lot of learning to do.