Wow, I hadn’t heard that.
So, if he had somehow successfully barred that adjacent stairwell door, he would have forced the police/SWAT to funnel down the long hallway. His double door forms the end of that hallway on that wing of the building and he had cameras pointing down that hallway. He planned to ambush the police/SWAT.
Yep. That hallway would have been a 100 ft. long kill zone.