I think it's really sad that you posted your question in August and no one has replied to you. I hope what I have to say will help you.
If you are joining your child, and he shows you he doesn't want you to join him or he pushes you away, then something is wrong with the way you are joining. There is probably something about your joining that is distracting or uncomfortable to him.
Firstly, you may be too close to your son. He may want more space, so if he pushes you away, quickly move further away, showing your son that he can have control of where you are in the room and showing him that you are excited about the fact that he communicated to you that he wanted you to move. You could say the word 'move' as you move away and move in a fun exciting way, and actually tell your son 'thank you for telling me to move.' Fell excited that he just communicated one of his needs to you!
Secondly, examine how you are joining your son. Are you following his actions and sounds accurately? And, most importantly, how do you feel when you join him?
When we went on our Son-Rise intensive, we were told that when we joined our son we should focus on the joining so that we could find something pleasurable or fascinating about the ism for ourselves. We were taught to experience Philip's world from his eyes if possible but also to love his isms so that when we were joining 'there was no where else and nothing else we would rather be doing'. Are you able to feel happy, relaxed, excited, fascinated etc when you join your son? When you can love his ism, he will see this in how you join, and your son will open up to you more.
Sepali, I hope this helps and I wish you much joy in joining your son. If you are struggling with this, I highly recommend you get a phone call with one of the family counselors. 'A dialogue' could transform your programme.
best wishes to you,