Child to attend tribunal?

Hello,
Last year I attempted to renew my son's DLA, it was rejected twice and is now going to tribunal.

We attended the tribunal date to be told to come back another day and bring my 13yr old son with me so they can question him on his difficulties.

I've never heard of any other child having to attend the court... has anyone else experienced this? It seems so wrong to me.

My son is highly anxious, and is terrified of appointments etc. (Which is stated repeatedly throughout his DLA papers).
I gave up work a couple of years ago to care for him full time because he could no longer attend school due to anxiety.
He is 13 and has a diagnosis of Tourette's syndrome. He has a history of poor mental health, including suicidal thoughts.

My gut is telling me that it's not right to subject a child to such a stressful situation, especially when regular doctors appointment cause him so much anxiety.

Happy to give more details if needed.

Any advice at all would be hugely appreciated.
I'm so worried.