If no windshield damage, air bag "whiplash" may have killed him. Old news, on this topic.
Injuries associated with airbag deployment
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There have been multiple reports of head and neck injuries related to airbags, mostly (but not uniquely) from the USA. Injuries include facial trauma, temporomandibular joint injury, decapitation, and cervical spine fractures.
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CONCLUSION
Airbags have been fitted into cars for nearly 50 years, although they have only been commonplace in the UK for one decade. During this time there have been numerous reports of injuries directly attributable to airbags, with some calls for them to be removed or deactivated. While accepting that these injuries occur, most (up to 96%) are comparatively minor. Most occur with the larger system used in the US, although UK airbags have been associated with a wide range of injuries.
There is no doubting the overwhelming evidence that airbags are effective at saving lives and preventing serious injury, particularly if used with a well fitted three point seat belt, and any injury attributable to their use must be seen in light of this knowledge.