The fusing 'delays' were not excessive per se and the Argentinians were well-aware that they were dropping ordinance outside of the normal self-frag avoidance criteria. Indeed, from the outset they set the fusing at quite an aggressive arming profile. They were technically proficient, they knew the attack profiles being used and the pilots themselves displayed an incredible amount of skill and accuracy during weapon delivery. Hitting a stationary vessel with a good CCIP + height-sensor with a dumb bomb is not a given during academic range work. Doing it against a ship underway, under fire, from a dynamic profile with visual aiming only is just incredible.
Bomb fusing is not just timing either. My knowledge of their fuses used has faded with time but in essence there was either a mechanic or a combined electro-mechanical fuse arming wire / wires. At weapon release these are pulled from the fuse arming vane as the other end is attached / connected to the aircraft pylon. Airflow is then free to drive the arming vane and the constant-arming governor until the preselected arming delay elapses (I think they had 2 to 18 seconds available). Only then is the arming train in mechanical alignment and able to function. At impact (as they only had impact fusing) there is then an additional delay set for correct weapon effect (impact, relay, detonator, lead, booster then main explosive charge).
Even without the folklore of the 'BBC commentary' the Argentinians had wound the arming delay back to minimum (2 seconds?) and way below the safe level given in the tables and even shortened the arming wire routing, to bring the weapon arming process uncomfortably close to the aircraft. The failing to arm or failing to fuse was primarily due to 2 factors caused by the out-of-envelope delivery profile. First was a known phenomenon of weapon instability in pitch when ejected from the pylon, causing brief arming vane stalls, which is not usually a factor during normal deliveries. The second was from the nose fuse collar shearing due to either impact grazing angle or surface skip. The collar shear was another safety feature designed to reduce the chances of unintended detonation should the weapon be dropped during loading etc but it also worked against them.
It's best to think of the Argentinean efforts as a technically proficient operator pushing the weapons to the very edge or even beyond their capabilities. As an example of their skills and knowledge the mechanical re-gearing of fuses to allow for slow-speed arming when delivered from Hercules wing pylons will give you an idea of what they could do, even in a hurry.
I think the folklore is just too strong to be overtaken by reality though and it is simpler to state or imply that they didn't know what they were doing. But they did.