Years ago a truck driver told me if an accident with an animal is unavoidable the best thing to do is floor it, and try to knock the animal away, thus minimizing damage to the truck.
I am not sure if I buy that, but crashing is certainly a worse option.
Truckers do not swerve to miss deer they run them over lots less damage that way. This guy most likely dozed off then rolled it. I deer is just a handy excuse.