Get it in writing....
Greetings and salutations....
The problem here is that times have changed. In the day, the unwritten policy at NASA was that once the mission was over, pretty much everything that was not nailed down was up for grabs and it was fine that the astronauts took stuff with them. However, now, for whatever reason, NASA is backing away from that policy and claiming that it did not exist. Hence the object lesson of why all of us should get promises from management in writing.
Now, I agree that it would be great for the notebook to be on display in the Smithsonian, as it is a way to return to, and be close to, that time in the space program when the entire world held its breath over the survival of the crew. However, I should point out that quite a number of the folks that have bought space artifacts have, indeed, put them on permanent exhibit in various museums. It is not like this is an artifact that is like a fine original painting by one of the old masters, that is worth contemplation for years.
The fact that NASA has ignored the notebook for 40 years indicates it has been abandoned, and, so, belongs to the person that has it. Shucks, NASA has a long history of dumping or selling off historically important artifacts. I cannot recall where it is, but, I remember reading in Sky and Telescope some years ago about a tempest in a teapot over an amateur astronomer who had used one of the heat shields from an Apollo command module as the dome on his observatory. There have been a number of other such things that have shown up for sale over the years, and, no one seemed to care.
SO...call it salvage and let the guy sell it
Pleasant dreams
dave mundt