It was as if he said the pilot was thinking about the time and space he wished to enter rather than having controls where you touch them with your hands. He also said that the humanoid pilot appeared to have been "bred" or genetically engineered for this task. Because when U.S. military or secret agency personnel tried to use this type of headgear they "lost it" and some never returned to "normal" earth born human consciousness.
Now I'm not 100% sure I read all this in Corso's book or whether this is a compilation of several books like "Above Top Secret" by Timothy Good printed in England but it seems to me this is one of the comments he made regarding testing this equipment by humans. It didn't work and several humans were lost as functional human beings trying to use this equipment.
However, that doesn't mean humans on earth didn't eventually reverse engineer this type of equipment for use by "Earth born Present day humans either" when our people have traveled through time and space to other worlds and dimensions since 1947. If you were wondering why this has been suppressed it is because of the Alien worlds or times and the time travel technology being so incredibly dangerous for terrorists and crazies to get a hold of here on earth in this present time (1947 to the present 2018) or also into the future 10,000 to 20,000 years.
Also, this gives humans the options of creating time lines where some humans actually survive ANYTHING.
So, the genetically engineered pilot's consciousness specific to him or her or it was the key to the ship so no other humanoid of any world could pilot this ship safely with his or her or it's brain.
So, you didn't need any physical keys other than the pilot because no other pilot would ever be able to pilot the saucer.
So, if someone killed the pilot or the pilot died for some reason no one could ever pilot the ship successful.