One could argue that whether or not Truman woul have bombed white folks is a political issue that would be discussed in politcal science course, not a history course.
If Trump had bombed whites, how badly would have hurt him, if at all, in the 1946 and 1948 elections.
Also, political science departments offer undergratuate and graduate courses on the presidency where Truman can be studied in depth.
That could include comparing Truman with FDR, Ike, Kennedy and LBJ & Nixon on this specific important matter.