I do think a child being violent and constantly disruptive needs to be sent home. However, just sending the child home will not fix the problem. If there is an underlying psychological and/or parenting problem the child and family will need considerable help. And it's often a problem to get the help that's needed.
A school can get additional help from behaviour support groups in the local LEA, which may help. But it can be a long and difficult fight with LEAs, etc to get the required input.
My DS was excluded for a couple of days at 5 - he then settled down. Eventually he was diagnosed with ADHD and associated problems - while I have no problem with him being asked to leave the school because his behaviour was not acceptable, I do have HUGE problems with the lack of support and advice offered to help the family cope, get a diagnosis and indeed for my LEA to even assessment my son's requirement for a statement. Fortunately, I'm an intelligent and extremely persistant woman who won't let it rest - I kept on at my LEA to get things sorted, but it can be extremely difficult to do.
I think the Government is sending very mixed messages to families. On the one hand they are encouraging mothers to return to work as soon as possible, but as soon as there's a hint of behaviour problems, it's now proposed that the parent (read MOTHER) stays at home with the child.
I think it's time that more respect and consideration is given to the parents who do stay at home to look after the children - I realise that it's not always possible - but I do think in the long run, it might be the best way forward.