My foster brother has learning difficulties and came to my old secondary school for a short stint (I was in year 11 at the time and he was in year 7). He found learning and behaving incredibly hard and just didn't turn up to lessons. It wouldn't be at all odd to look out the window in a maths lesson to see him crawling around under parked cars with 2 or 3 learning assistants desperately trying to find him. He got moved to a special school (they just seem to go bowling and to the cinema constantly) and he finds it much less stressful.
I don't think these kids should just be chucked out the education system, apart from anything else, later in life they'll be living at the tax payers expense. At the same time though, I used to hate the fact that the teachers in my classes often had to wait for some idiot in the back to behave, or pause halfway through what they were saying to tell them off, or listen to them talking during a test. It is off-putting and it isn't fair to those kids who really do want to learn.
Most disruptive kids already have 1-1's and extra learning support, I'm not sure what else the government could be doing. The system isn't perfect by any means but at the same time I can't see how they would improve it without negative counter-effects elsewhere.