Because their guns weren't empty yet.
There was no continuous shooting after Finicum was down. He was shot 3 times. Any shooting after that was the teargas/pepper spray rounds and flashbangs being shot at the truck to encourage the occupants to give up.
Did they still feel threatened?
Maybe the old standard: “He was coming right for us!”
*spit*
Still, even after Waco, people expect Justice? The ‘law’? It’s been ‘us’ vs. ‘them’ since the early 20th century went we went full retard and elected Wilson, a Socialist 4x and, the coup de grace, LBJ....Clinton, Bush(s) and Zero are just symptoms.