Those governors and mayors are realistic: They know that any appeal for calm would fall on deaf ears.
Those hooligans regularly commit crimes in their daily lives. They certainly are not going to listen to reason during a riot.
All the more reason to shoot them on sight.
No matter how strong the temptation, we simply cannot shoot people on sight.
This is not China or South Africa (in apartheid times).
The various groups have no choice but to tolerate one another the best that they can.
We have no choice, for no group is going to leave this country. We are stuck with one another.
There will be another orgy of riots in the future, tomorrow or next year or the year after that. That will happen even if the police officer is a non-Caucasian.