Will what do the other children do in order to be nominated? I doubt your son is the only one who is not nominated. So it might not be because he has special needs. It might simply be that another student met the criteria for nomination when other students didn’t.
You can always find out from his teacher what type of accomplishments the students get recognition for and work with your son to make it a reality for him. If she tells you things that are simply impossible for your son to accomplish because of his disability you should gently but firmly remind her that she is essentially denying him access to an important part of his education and suggest ways for him to participate. If she does not get this you need to remind her that your son has a right to this access.
It might help to speak with the teacher and whoever was involved with the development of his IEP. You can ask for adjustments to the plan. You can also request an Aid for him if you think one is necessary to make sure he is able to participate as equally as possible in school activities.
I've attended many IEP meetings with parents as the "regular education" teacher. I'm generally surprised at how little most of the parents have to say.
The meeting is for you, and it is the best time to voice concerns about any aspect of your child's education, including his social interaction with peers and his sense of community within the school.
The only group of parents who are vocal in these meetings are the parents of gifted children, and I promise you they're not shy about laying out their goals for their children and asking how the school can help with those.