Some wise people on here. I agree it has to do with your DH's own upbringing (and how his father treated him) as well as being away a lot (and therefore, frankly, out of touch with how things are normally done in your home).
I have two sons (10 and 12) and DH can really shout them down at times. He does not seem to be aware at times that he is shouting. I always always always tell him, at the time or after, that he is acting aggressively and that eh escalates problems. The thing is, his own dad was very authoritarian.
My parents were "soft" (not really) lefty parents who treated us pretty much like adults once we started secondary school. They could get angry or (worse) disappointed, but never shouted, instead we talked and talked about everything. They always tried to understand us. We had independence from an early age. My brothers and I all have a good relationship with our parents. We all made mistakes along the way though. But I think you have to let kids make mistakes, and then be there to provide support.
I do worry now the DC get older that our parenting styles are starting to differ.
I always pull DH up on his behaviour, and give him alternatives to deal with it in future. I say I will not undermine him, but neither will I stand by and accept him treating them in an aggressive manner. To me shouting is aggression, to him it is not a big deal. Is that a male/female thing I wonder?
Have a calm chat with DH in the morning, where you don't accuse him, but look for solutions and how to handle these situations in future. Don't leave, or your son will feel he is breaking you up. But do be supportive of him!