No it wasn't. The protesters were allowed in by the Capitol police who opened barriers and doors and stood by while they entered the building in an orderly and peaceful manner.
They could have kept them out if they wanted to. It was a planned event where everyone had prior notice. Some serious questions need to be answered on why there was a lack of Security Personnel, Equipment, and Security Measures. Also crowd dynamics 101. Review footage and go arrest the instigators and leaders. Epps and dude on the scaffle giving directions. Lawyers of those arrested for trespassing need to identify and subpoena their butts. That includes the fence cutters. For starters. Then we can get somewhere.