I am not sure my DH has ever been one for serious discussions with our children; son, or daughter. It is just not his style.
They are both around 50 now, and any serious talks and discussions emenated from me, or the children. I still have long deep discussions with both children, usually on the phone, about anything and everything, from personal subjects, to political and philosophical matters.
Because you think your husband should be having serious discussions with his sons, does not mean he has failed in anyway because he doesn't, it just means that you are expecting him to be something he isn't. Neither my DH or our son are in to serious man-to-man discussions.
However , ours is a family that does an awful lot of talking and have discussions on anything and everything around the dinner table, or sitting back in the living room in the evening and at various times during our children's youth they heard our family values on many subjects, put forward and discussed in family discussion. This included sexual matters.
I am not convinced that the 'I did this in my youth, it caused no end of problems so don't do it yourself ' is a good way of approaching problems anyway. We just had family discussions, for example, about how unplanned pregnancies outside committed relationships affect the woman far more than the man and that it behove both children never to have unprotected sex or relie on a partners assurances. The discussions would then move onto considering whether you could swim in a swimming pool full of jelly, or whether you would just sink.
But the messages were heard and, as far as I know, informed their behaviour.