I havent RTFT but it sounds like positive behaviour reinforcement to me. It's far better to reward good behaviour than punish undesirable behaviour.
Punishing kids, particularly those with SEN often leads to them feeling demoralised, believing they can only be good or naughty (particularly the more literal kids) and thus it becomes a self fulfilling prophecy.
My own DS was one of these so called 'naughty' kids. At his school at the end of each term the kids who hadn't been told off at all got a party with drinks and cake. Those who had had a minor transgression or two got to go, but no treats and those who had had worse sanctions weren't allowed to go. In DS' words "The good kids get a party, whilst all the bad kids have to go off to another classroom and do work."
DS has ASD. He would get punishments for things related to his condition that were beyond his control, such as when he stimmed when he found things hard to cope with. Because of this as soon as he got told off and was told he'd lost out on the party he stopped behaving. When the head asked him why he'd suddenly started acting up he said there was no point in being good any more as he'd already lost out on the reward.
The head teacher realised they'd not thought of it that way and they have now adjusted how they do things for the kids with needs. When DS told me which kids missed out on the party with him the names he reeled off were all the kids with ASD, ADHD, Dyspraxia etc.!
So now school rewards all the behaviour they want more of. Punishments for undesirable behaviour have to be immediate, relevant, objective and measurable. There is no point re-punishing a child for something that happened days or weeks ago.
I suspect they are rewarding the behaviour that they want to see more of and are using this time as a way to explain to the children which behaviour was responsible for this. They will likely also be using this time to improve their social skills too. When DS attended a social skills group in his younger years they were played out like a tea party. And even if there's no SEN, kids who are acting out could obviously do with a little help with social skills anyway - as could many of us!