The steering grip illustrated above is wrong! nor the 10 to-2 grip and neither the 8 to 4 grip are proper. 9 to-3 is the only basic grip acceptable. The wheel is designed for such a grip, with special intendations for the thumbs.
The steering grip results in the widest possible hand deployment which creates the biggest leverage over the steering column for accurate and agile steering input to a maximum amount of 270 degrees of steering, sufficient for any avoidance manuever or grose steering corrections required in a straight road. In 8 to-4 or 10 to-2 the leverage is reduced and the grip is not supported by the spokes of the wheel.
With a reasonable seating position aligned, 9 to-3 is going to be more ergonomic due to a more neutral position of the hands at the shoulder, arm, forearm and wrist. In 10 to-2 your arms will be held high (although rested against the wheel), so the shoulders and arms are stretched forward and the forearm and wrist are twisted.
The subject of the airbag is important but should be referred to as secondary. The operation of airbags, seatbelts, crumple zones and other passive safety instrumentation is part of our "secondary safety" which refers to our passive protection during a crash, while our main concern is for our "primary safety" which describes the active ability to avoid the crash or reduce it's magnitude.
Our primary safety is hindered in any position other than 9 to-3, particularly at 8 to-4. This can increase the risk of a collision that would result in airbag deployment. Furthermore, there are other injuries that can be caused to the body or arms in a colllision, that do not involve the front airbag, and these can be eliminated by increasing steering control, but not eliminated by gripping the wheel at a certain way during a crash. Besides, the risk of a collision involves other parties like your passengers, pedestrians and occupants of other vehicles, who couldn't care less about abrasions to your forearms because you held the wheel at 10 to-2.
The whole disscussion is out of context since airbags should not cause damage to the arms unless held higher than 10 to-2. At 10 to-2 or lower there should be no harm. Many American automobiles have bigger airbags which are more dangerous to the arms, but there still is no serious difference between holding the wheel at 9 to-3 or 8 to-4. The arms should be forced aside by the airbag or pinned down at the knees.