Just hanging out without doing any damage, without assaulting or threatening anyone? What is wrong with that? Going into a public building without doing anything wrong, without causing trouble, that is allowed, is it not? That would apply to a police station, a courthouse, or the capital. If you do damage then you have overstepped the allowable line.
I believe that a significant portion of the people in the capital on 1/6/2021 did nothing wrong.
BTW, do you see anything wrong/fishy/suspicious in the fact that our world famous intelligence community were unable to find out who leaked the Dobbs decision, or who brought cocaine into the highly secured White House, yet somehow were able track down every person that was anywhere in the vicinity of the capital building on that day? I do.