If he has severe learning disabilities then you NEED it documented for the school to provide the proper supports.
Trust me when I tell you that school will only get worse if he is not being taught during class. If he gets used to being retaught by the tutor later in the day - the class time will eventually become a time for acting out. He will be so frustrated at not getting things, he will tune out. Well, I guess that is not a guarantee, but it does seem to be the natural progression for a lot of our kids.
Homework battles are not fun. My difficult child and I ended up in tears most nights.
Ask the teach how long it should take him to finish on average and if it is taking longer, have him stop and enjoy some play time. If the teacher sees things are not getting finished she will be more apt to agree to difficult child needing help.
As for the title of your post. This took me way to long to learn. It is OK to walk away, tell difficult child that you will be taking a break or just ignore him. It is OK. It is part of parenting. You will be teaching him how to handle his own anger with his own children some day. Hopefully, he will be able to learn from it now and use your tools in the same respectful way now. He should be able to recognize his anger is getting out of control and know what to do in that situation. Taking a 10 minute break is a good tool to have.