The Congressional Office Buildings as well as the Capital and CVC are public buildings. The public can enter the buildings during normal business hours (minus extenuating circumstances such as a lockdown , special events, construction, etc.) and are only required to pass through a metal detector and x-ray machine.
Of course they can, but people who are going to be disruptive and disrespectful should not be allowed to enter. I would allow one or two of them in at a time. They are infringing on everyone’s rights and disrupting business.