Any player of any worth that is still under contract won’t be released. They may be sold later on, but not released. The thing this statement could confirm, is the U23 and academy details. Nothing to report in first team really.
He's still under contract. I'm not sure when retained lists started including players that are not out of contract, but it doesn't make a load of sense.
It's one of the things we don't get much say in. Depends who the secretary is, how it's formed etc. If I can find previous years, I'll post the links. 2020 - https://www.barnsleyfc.co.uk/news/2020/june/retainedlist2020/ 2019 - https://www.barnsleyfc.co.uk/news/2019/may/retained-list/ 2018 - https://www.barnsleyfc.co.uk/news/2018/may/retained-list/ 2017 - https://www.barnsleyfc.co.uk/news/2017/may/retained-list/ 2016 - https://www.barnsleyfc.co.uk/news/2016/june/retained-list-confirmed/