Did you feel like you wanted to control your parents? He wants to be in control at all times - so as not to get hurt, I'm sure. It has not sunk in for him yet that we are not like the birth family and we will not hurt him. So he doesn't trust that yet and is frustrated that we control his life to a certain extent (keeping him safe, etc.). We give him as much control as is safe for him emotionally and physically, but he wants to control what we do, even to the point of telling us when we should brush our teeth, when and what we should eat, how we should walk...it goes on and on.
Yes, you are right. Even to this day, I need to be in control (of me). Sometimes, when our confidence is shot, we need to be the ones to make decisions, because a lot of the time, the decision were taken away from us, and those decision hurt us. This rings true with most of my life, even into adulthood. I don't like anyone else even trying to control me or my life. But once confidence is rebuilt, it is not as painful taking the lead from others.
As a child, I often bossed my doll around, saying that is not the way to do things, and showing my doll how to do things the 'right' way. My parents were the controllers, and I never had the opportunity to control anything in my life (until I was in my 30s and walked away from them), hence controlling the doll and overly controlling myself.
Looking back on it as an adult, we need to control our own life. I don't generally control others, because I know what it is like to be controlled and have my right to choose taken away from me.
But there are times when we (the proverbial) 'try' to control others in our life to compensate for things not being 'right' in our own lives. When we 'try' to control others in our life, it is often because we are trying to compensate for not having the 'perfect' life or the 'fairy tale' we read in stories. We spend a lot of time trying to perfect everything around us, because if it is perfect then there is no cause for getting hurt (not logically true, but often the reason anyone does anything isn't logical but emotional). This is the protecting from getting hurt idea you mention.
Children do need to respect parents, and understand boundaries. They need to know that these boundaries are there because you love them and want to protect them. Sometimes we kick at boundaries because we want to test how far we can go without 'pi$$ing' adults off. This sometimes can be misunderstood as a gauge of love, and that is unhealthy behavior. Because love is not how much someone puts up with...so managing these behaviors (if you suspect this may be the case) is a good thing.
It must be hard to know how far to push when a child has suffered a trauma. But, just do what you would with any child, and that includes setting boundaries and being tough about keeping them safe. And, do what you are currently doing and let him make some decisions for himself. Or put it on a roster of who gets to decide what you eat that night, so that he knows sometimes he can make decisions, and sometimes you can. If he knows that there is an opportunity for him to make a decision coming up, then maybe there will be less anxiety when you make decisions for him.
Keep doing what you are doing. Know your son is lucky to have you in his life - someone who cares so much to be here on this forum looking for support, understanding and information can't go wrong in my books. And, maybe try to build his confidence as much as you can within the boundaries of safety. Occasionally doing something silly so he knows that he is not the only one being laughed at, might help if he can learn to laugh with you.
Bless you and your family for caring for your son.