The manuals are tailored to the operator, which is why they list the operator's airframe serial numbers and reflect the equipment and options on your specific aircraft. That also means that where there is no technical objection, the manufacturers' manuals will reflect company procedures. SO, it is more likely a company policy than an Airbus one.
By the way, I think you owe Flyingstone a big apology - he made a mildly mocking comment about an authority figure (in this instance AB, but it could have been anyone) telling you how to suck eggs, and you went nuclear. The arrogance, pomposity and attitude was all yours, not his. If you feel the need to rigidly apply such pointless SOP and enjoy debating such issues just for the thrill, then your 35 years have been wasted.