I think it's fairly clear that this fire was not intended to spread and had little chance of spreading.
To be clear, I'm not saying what she did was right--but I am saying that if we look at intentions and what was likely to happen, this clearly was not done with the intent of destroying anything but property.
And to be clear, if you look at the George Floyd murder and protests, and your biggest concern is the torching of two unoccupied police cars, you aren't concerned about justice or public safety.