Blowing in the Wind

I don't get it. My dad is well mannered, very considerate to others beyond normal expectations. Yet, he has this habit of blowing his nose at the dinner table. I don't mean a gentle quiet blowing of the nose, but rather a louder-than-a-trumpet (Al Hirt style) blowing of the nose. I don't see others do this often, but when I do it usually is someone around my father's age or above. It must have been socially acceptable in the forties, fifties and so forth to blow your nose at the table. I must make a note to myself to research this further; because it certainly does get on my nerves. Other than that his table manners are impeccable.