Instead of trying to over-analyse the marking system to the nth degree, and you know the difference between right and wrong, why not simply drive properly?
Crossing hands is all well and good at low speed manoeuvring or in a dire emergency, but to do so habitually and subconsciously compromises fine control, usually at a moment when you need it the most.
What would happen in the event of a crash, should the airbag deploy? If you are holding the wheel properly with each hand holding only the respective half of the wheel, the airbag cushions your head against impact. If you're crossing an arm over at the time, your arm is propelled into your face with some force.
Consider also taking a bend that turns out just that little bit sharper than you expected, or you need to add some more steering quickly to avoid an oncoming car who's cutting the bend (probably driven by some numpty crossing his hands!), pull-push can add - then rapidly subtract - that extra steer with fine control and very quickly, whereas arm crossers will find themselves tied in knots as they physically cannot twist their arm round any more.
Finally, don't rely on "getting away" with lesser faults in any testing situation. The lesser faults can soon add up to bigger ones. What starts as a habitual and sloppy "not worthy" fault is usually a serious fault waiting to happen; all that's needed is that unlucky set of circumstances. Then, of course, we would read the threads complaining about "luck" on driving tests - had the skill taken over, any "luck" would simply have been negated.