It’s a valid scenario: Sessions doesn’t want to be the bad guy, and neither does Trump if it would harm prospects in 2018 and 2020. Too many negatives. Race war is already a possibility. There’s actually more to gain politically by not prosecuting, and just letting it all hang out there flapping the breeze.
Any race war would burn itself out in a few short weeks... Once the Black Community marches and destroys everything they come in contact with, they will be forced to stop their marches of destruction simply because to further burn and loot beyond their traditional haunts would bring the Armed and Furious that would end up shooting a large group or groups as necessary to end the violence.