Regardless of the legal requirement to wear a seatbelt, hope, it would be interesting to know why your husband (presumably a professional driver) would not choose to wear one. I accept there may be circumstances when he is carrying passengers that he might not wear one for the reasons already outlined. However, that was not the case here.
Tests have overwhelmingly shown that wearing a seatbelt reduces the risk of serious injury in all manner of collisions and that this advantage far outweighs the likelihood of a seatbelt causing injury because, for example, an occupant becomes trapped by wearing one. In particular, if a car is fitted with airbags, the protection they provide is not only reduced if a seatbelt is not worn, but the deployment of an airbag can itself cause additional injury if the occupant is unrestrained.
I’m sorry to open up your straightforward question to a wider debate and I’m not having a go (your hubby can do as he pleases as far as I’m concerned). I’m just genuinely intrigued as to why anybody would choose not to wear a seat belt.