The only reason for hedging like this is to sanitize the file first. Kerry is a weasel. (Sorry, that's an unintended insult to weasels.)
Yes, once signed someone's record jacket essentially becomes public property.
The purpose behind demanding that Kerry sign the 180 is not to allow him to release selected portions of his file, but to allow others to access the entire file without Kerry being a gatekeeper.
Kerry can't control access once he signs the Form 180 and that is why he never will. Changing the contents of the record jacket is dangerous and nearly impossible. There are multiple copies of records in many different places. It'd require a truely vast conspiracy to really permanantly alter someone's record jacket.