I suspect the implication here is not so much "note it on a fag packet until you get back" but one of "note it anywhere you like as long as it never appears in the tech log".
Just suppose. If a company were to have a culture where Capts are, shall we say, discouraged from entering defects in the tech log (the threat that might be used is quite obvious) then how else do they save their necks, and those of their colleagues? In todays dead employment market the pressure to comply with this sort of thing is very very strong indeed, and how many would knowingly put their job/career on the chopping block over this? Not many, I fear.
The really depressing thing is that if any of this is true then nothing has been learned in years and years, and that would be a bloody scandal.