It saddens me that a stupid test, for which they are exerting unwarranted pressure, could result in action that is wholly unfair. DD & DS are under SEN which is more pastoral than anything. I told DS that I'd like him to do well, if he achieved the average he could have a treat. (Which gave motivation for revision - truth be told though, he could have achieved a crap result and still have been treated as the school put so much pressure on the students.)
He has autism I would say it's discriminative to hold any behaviours against him, especially at a stressful time where routine has changed, so the emphasis is all SATs based, so the change in routine alone will affect his behaviours, not to mention stress, pressure, any pupils who are being cocky.
I hope you get it resolved, I would feel inclined to say, your inclusion policy states ... therefore you have no basis on punishing DC, because that would be discrimination and against his human rights.
I'm seldom one to ever say the above, I certainly believe it to be the first time I'm even suggesting that human rights be mentioned. Hopefully it'll scare the school into thinking we are being harsh on all the children in Y2 & Y6, this is one of the results of applying pressure, on a child who that will affect more than most.
I really hope you get it all sorted. When away from home, there'll be more than your DS with potential behavioural issues. They don't know how any child will react to being away from home. So it's not an excuse.