How about you just give us a source that if you write something and there is “even a small chance” someone will see it, that you are over on LH?
Also, even if it would definitely be seen, it might still be muttar. IIRC, you are allowed to tell someone LH if you need it in order to vent your emotions. Since that is the reason people write in diaries, it sounds like it could work.
I’m not saying I know it is muttar; I’m just saying you are making stuff up.