Meeting with Cub leader and Group Scout Leader

I have an undiagnosed 8 year old boy, who as far as school are concerned is being treated as ASD while undergoing the diagnosis process, he is already diagnosed as having PTSD following something that happened in 2015 (so 4 years)

He went through Beavers, I am the Beaver leader so it makes things a bit different, 
He got on ok, but like any child on the spectrum he had his moments where he struggled to cope with one thing or another.

He moved to Cubs last October, he had met the Cub leader and Group Scout Leader (GSL) several times and personally I am of the opinion that they felt any times his behaviour was not "good" at Beavers was because he was playing up with mummy being the leader. I feel myself that if you observed what had led to these fairly rare occurrences  that they were related to his ASD traits/tendencies.

When he started Cubs I explained to them that he has "issues" and that it would be good if we could discuss them at some point, all I kept getting from them was that
"he is fine"
"he is settled"
"nothing to worry about"
I am sure this is because it goes back to him "playing up for Mummy" and them not understanding that he felt "safe" to show his true self around me at Beavers, but has been masking at Cubs

A couple of weeks ago an incident happened when my son got pushed accidentally, this led to him getting distressed and chasing after the child, part of the distress is probably due to the fact when he got pushed he chipped his tooth (only tiny, hardly noticeable, but would have had an effect on him!)
This led to him being excluded for a week.

I have no issues with the exclusion if he did things that are against their guidelines.

My issues are with the fact that however many times I tried to explain that he has "issues" we need to discuss I was fobbed off, quite possibly treating me as a leader and not as a parent.

I have a meeting this week with the Cub leader and the GSL, I am fairly sure they are going to try and go on about the incident and how they were perfectly within their rights to exclude him (again not what I have an issue with) I am not interested in discussing this side of things, to me that is in the past and he has been punished for it.
What I want to go "armed" with is info on why they should have listened to me first and what they should be doing to properly support me and him etc.

I have printed various pages from the Scouting website about Autism, Scouting Inclusion Policy, Listening to the child and parent.

I would be interested to know if anyone has any advice of what to say, do, how to handle things, any policies, guidelines etc I should take along with me etc.