Don't see how stealing the documents (whether they were classified or not is immaterial --- they didn't belong to Trump) supports barring him from office. True, 18 USC 2071 provides for such a disqualification, but it's doubtful that this is constitutional. See
http://www.ronpaulforums.com/showth...n-2024&p=7127260&highlight=Powell#post7127260
The 14th Amendment, on the other hand, does bar someone from holding any office under the United States who, having previously taken an oath as a federal officer to support the Constitution, engages in insurrection or rebellion or gives aid and comfort to the enemies thereof [it's a bit unclear whether "thereof" refers to the United States or the Constitution; probably the former]. Congress can remove this disability by a 2/3 vote of each house.
It's patently obvious that Trump violated his oath to support the Constitution, not only by sitting on his butt while rioters invaded the Capitol but also by his attempts to get people to ignore the election results and declare him the winner via unconstitutional means. But whether these violations are covered by the 14th Amendment (which, after all, was aimed at former Confederate officials) raises some thorny legal issues. Since Congress has the power to remove the disqualification or let it stand (assuming it applies in the first place), SCOTUS might very well say that it's a political question and punt the matter to Congress.