I don't think anybody on this thread who is advocating for children with SEN has said they should 'get away' with anything.
If a child has been violent and physically harmed another child there should be appropriate consequences for their level of understanding of what they have done. Whether that's some days exclusion, lost play times, a visit to the head etc I don't know. As a parent I would do whatever was necessary at home too to help them understand that they acted wrong.
A child with SEN that has lashed out because they are overwhelmed, over stimulated or have possibly been intentionally or unintentionally wound up by another child is different to a child that doesn't have any SEN and has just lashed out for whatever reason. Children prone to this behaviour are being failed by the system if they don't have adequate supervision in school, and therefore the rest of the class are being failed too.
The result is the same whoever the child, an innocent child has been hurt in the process, but the child needs to be dealt with in a way that they understand.
My child is autistic, but has never been violent to anybody. During a meltdown he is more likely to harm himself or just scream until he is blue in the face. If he suddenly reacted in a way that is out of character for him and he hurt another child, i wouldn't expect him to be reprimanded in the same way as a NT child, but I certainly wouldn't brush it under the carpet and do nothing.
My child is the gentlest, kindest soul. They are thoughtful, quiet and tries so hard in school. They do have tricky days and do need a high level of support, but causes nobody else any harm and doesn't take away anything from anybody else. That's not to say as they get older they won't change and won't start to react to sensory overloads in other ways, but I would expect them to be receiving the right level of support at all times. I am just pointing out that many children with SEN are not violent but may suddenly lash out in a moment when they don't know what else to do, and that doesn't mean they should be home schooled or sent away elsewhere.
Many of the sweeping statements on this thread are so insulting and unpleasant. Some I recall are referring to children, actual children, as 'special needs' and saying things like they are 'over diagnosed' 'validated after being violent' and god knows what other absolute garbage.
Everyone's priority is their own child and rightly so, but it's everyone's job to be pushing for better in the education system.
SEND is massively underfunded and has been in crisis for years. This is the reason why so many children are not getting what they should be in schools, not because of 'shit parents' who 'coo' over their children and think they can do no wrong.