The person was white. Had he been black, they would have raised hell with the police even questioning what he was doing.
Well I guess we'll have to wait until black people feel safe enough from law enforcement in their own country to arm up and take over a federal building to know if your wild speculation is true.
Posing a threat can come in many forms. The white guy did it, was shot, and you're OK. Michael Brown and Tamir Rice did it, were shot, and you chastise police. The only difference is color.
Michael Brown attacked an officer. LaVoy Finnicum engaged in domestic terrorism. Tamir Rice was playing in a park and hurt no one.
Tamir Rice was waving something that had been altered to look like the real thing. When you present yourself as such, don't be surprised when people treat you that way.
In my State, someone can go into a bank, present themselves as being armed, and they will be treated like an armed robber when caught whether they were truly armed or not. That's how real life works. If someone doesn't want to be treated the way he/she presents himself, there is a simple solution. Don't present yourself that way.