He is not choosing.
He in unable to do the things you want because he is extremely anxious. This is not fun for him.
Even special settings struggle with PDA.
The PDA society has more info. You need to use different strategies to autism – and they may change day to day.
Children with PDA dx often struggle to retain learning if they are compliant as the effort of being compliant affects cognition & retention.
I recommend reading Barry Carpenter “pedagogically bereft” and anything by Peter Imray. Also books by parents of children with PDA. Outcomes are often not fantastic for PDA and conversations with parents around this and how they want education to look are important. Done so I’ll use of language activities might be useful