Oh come on...you can't honestly think that all this was necessary, can you?
500 national guardsmen would be more than enough to defend the Capitol from a similar attack. Make it clear to the crowd that an attempt to penetrate the Capitol interior unlawfully will result in them being treated as a hostile force. Napoleon broke the mob in Paris with grapeshot. Much as I truly loathe to say it, you cannot deny this would be effective.
I genuinely hate what I just typed...the walls do make sense (IF AND ONLY IF there is a new threat of another assault). Convinced myself. lolol