In Britain, the Queen may not enter the House of Commons without permission. This tradition dates back to the English Civil War, when Charles I entered the chamber with soldiers seeking to arrest its leading members. Each year at the State Opening of Parliament, the tradition is reinforced through a ritual in which the door of the House of Commons is slammed in the face of Black Rod, the Queen's representative, when he comes to summon the Commons to attend the Queen's Speech in the House of Lords.
Likewise, the President by tradition may not enter the House of Representatives without permission, There is no special reason to think that the State of The Union must happen next week, that the address must be given to an audience, or that the speech must be delivered in the House chamber. I hope the shutdown ends soon and the State of the Union proceeds normally, but the President cannot just barge into the Capitol and give a speech under our Constitution.