It does me. I can't find a historical situation where a federal building was taken and they didn't cordon the site nearly immediately, if for no,other reason than to stop random people from wandering in. But there's been no one to stop the press, random youtubers, or further militia from rolling up to the blockade the militia has set up at the entrance.
If you can find an example, I'd be fascinated to see it. I already looked at the BIA (cordon around the building within hours) and Wounded Knee occupations (every road for fifteen miles blocked on the first day) as well as multiple draft office occupations, all of which fit the mold of a nearly immediate cordon, so yeah, it seems a little unusual to me.