Golden time is time at the end of the school day where children can do fun activities such as going on the pc, playing board games, drawing etc.
I can understand why your ds feels resentful - perhaps you could have a word with the teacher and explain this. They might not tell you exactly what else is happening to the other child, but could perhaps tell you that other measures are being taken, and this might help your son feel less hard-done-by.
I used to feel resentful on behalf of the good children in my children's classes, because it seemed to me that there were schemes set up to reward good behaviour from the badly behaved children, but little or no recognition for those who routinely behaved well. Certificates were given out, but every child got one during the year - even if the teacher had to think up a really spurious reason for awarding it - a friend who was a TA at the school told me this.
Obviously children who are badly behaved can improve if given rewards and encouragement - nothing wrong in that, but I also firmly believe that the children who are behaving well, working hard and achieving their best need encouraging too!!
If they feel that they are never getting recognition for their work whilst they see other kids getting lots of attention/praise for doing what they do as a matter of course, they are going to feel resentful.
I'm not sure what the answer is (or even if I made my point at all clearly or understandably - my brain is failing, I'm afraid), but it seems logical that whilst there are some rewards when bad behaviour turns good, there ought to be further rewards to give all the kids something to work towards.