I'm not sure that I'd call it a 'get out'....This type of bodge gets my goat. I know 433.2.2 is a get out, but it also makes reference to 434.2.1, which specifically suggests reinforcing the protection of the wiring against external influences.
...Are you saying that, whenever you install a fused spur off a 32A ring or radial final circuit, you connect the FCU to the ring/radial with 4mm² cable, or use 2.5mm² with 'reinforced protection'?
... and, indeed, what if it's an unfused spur off a 32A ring final? Again, do you always use 4mm² cable (or 2.5mm² with reinforced protection) for that, as well? (the only upstream cable protection being the 32A MCB)
Kind Regards, John