Not commenting on what happened in this specific case, but how can someone’s ‘Ops Manual’ override e.g. the ‘in vicinity’ CASRs? Anything ‘non-standard’ should be in ERSA itself (or e.g.NOTAMs), so that ‘ordinary’ pilots can find information where it’s ordinarily found.
I understand the logic of having some kind of aerodrome-specific ‘comprehensive guide’, but the risk of it being overlooked by ‘outsiders’ seems obvious to me, even if it’s referred to in ERSA. Again, not saying that has any relevance to this tragedy,
As someone observed earlier, nobody straps in with the intention of operating in a way that increases the risk of a collision.