Aiwass certainly didn't keep a diary.
It gave him a sense of insecurity, as if someone was peering into his innermost thoughts. Just the act of writing it down evoked this feeling, even if, in theory, no one else would see his diary.
In such a case, if Aiwass were to write a diary, he couldn't possibly write the truth.
It was like sharing one's daily life on social media platforms—the content shared was of course edited, refined to emphasize the interesting parts, artificially stripped of the boring elements, concealing anything that might cause embarrassment. It might even involve laying down lies convincing enough for himself to believe, repeating them over and over in an attempt to alter his own memory.
—But conversely, reading someone else's diary ignited a sense of invasion in Aiwass.