I'm sorry, but if you require the deletion of what you said to protect yourself from the people, then you shouldn't be in a position of power.

> and stating bluntly what you really mean (and what you are concerned about)

In the end, people aren't judged for this. They're judged for the actions that they take, and then communications like this are used for context. If your decision is so bad that they had to make a FOI request to find out how spurious your reasoning was, then I don't see why you should have the protection of having no paper trail. That's insanity.