This is the same reason we were given when my son was in yr2. However, when I accessed his records this academic year(son now yr10), I found that 3 reports put in just after the SA, by CAMH, had told the school he had been poorly supported by previous school, if he didn't make progress he would need SA. We were never informed of this, he never made the expected progress, but neither has he ever been statemented. So effectively, though he was poorly supported according to the LEA his needs were being met!
I posted this on your other thread, don't know if you saw so have reposted.
I'd maybe be a bit concerned that your being told he is meeting national curriculum requirements - can they show you how, where, how often.
I mention this because I was given my sons summative assessments by one school, in lieu of his educational records. There was significant differences between the work even though it was marked at the same level; all the work was also homework (told by one teacher that when marking he looked at the previous level and moved the mark up by a whole level or sublevel depending on how much progress he thought child had made).
Because the next school wouldn't recognise son's difficulties I took a number of tacks with homework which I thought would be used for assessment purposes; left child to complete on own, level 3, I provided the usual amount of support level 4, I completed one piece entirely on my own level 7 (accepted). Reported end of year grades 4, 5, 6; which proved the child didn't need help - then I asked for summatively assessed work and told the school what we'd done, also queried why two subject grades reflected the higher levels child achieved while the subject where level 7 achieved was lowered (they can't answer). Suddenly they are a bit more helpful, though still trying to fob me off.
I have also tried to get all of last years assessed work remarked - guess what nobody is prepared to do it. Spoke to QCDA, LEA, LEA Curriculum Inspector, SENCO and child's tutor asked two colleagues. When I asked SENCO during a phone conversation I was told they didn't do AFL at school; she got off the phone PDQ. At a later meeting I asked what they use to mark if not AFL. Backtracked, denied that she'd said AFL not used, blah blah blah, grading still not explained. So despite only being given a level descriptor on reports it appears nobody can explain how that level was achieved .
Maths is the same, bumped up every KS test, meeting the schools needs not my childs.
Abusing level descriptors is just another means of fobbing you off an 'proving' your child doesn't need help, is making progress.
I would appeal.