Don't forget he has had no say whatsoever about having you in his life, whereas you did have total say about having him in your life.
And how does that give him a free pass to be rude. He is a teenager, not visiting royalty and if someone was coming into MY home and being bloody ignorant I wouldn't be too pleased about it either
It's more complex than rudeness though. If a young person is put into a situation by their parent and they are uncomfortable/unhappy what can they do? Refuse to visit, get angry or just go silent??
I completely understand why it's horrible for the Op, no one doubts that BUT is his behaviour acting out as result of the situation?
Op, as you say, your DH needs to handle the situation. He can force his son to say hello to you but will that just mask the situation?? My advice - focus your thoughts on your DH, it's his job and it may help you lose resentment toward SS. If he goes to Uni, you have 2 years left of his behaviour.
From my experience, often children are put in step family situations at younger ages and as they get older they start to vent their hostility (maybe the change of dynamic with older brother has brought it to a head). When they hit teen years the rebellion appears.
It's a tricky balance, what is normal teen behaviour that needs correcting vs teen behaviour as a result of the situation that needs care?? I think in most cases the Dad has zero skills (and motivation) to handle any of the scenarios so step mum ends up feeling resentful.
I think generally there is too little awareness of how difficult step parenting is vs the rewards. I've been there and wouldn't do it again!