Using you example the fact that a futility be found in error but then the error corrected by regulators and why the error took place, how the error was recognized and how the process of fixing it went would be information that is useful to future researchers.
Your argument seems to be that it is okay to hide such information for political reasons.
It has been quite a few years since the screening halt was lifted and more still since it was imposed.
Leaving aside the value to future researchers who might need to overcome similar issues, processes involved in imposing the screening halt and its subsequent lifting cost both taxpayer and NWBO shareholder money. It is reasonable for us to know what went on and not to guess but to know.