From reading Woodworth's Letter From the Raymond Street Jail, I get the feeling that he harbored an antipathy for people of color.
He took care to mention that "Negroes" shared their prison block.
His no-blood madness came out just around the time Dr. Charles Drew - a Negro!!! - developed a technique for storing and transfusing blood.
I believe the no-blood doctrine was born out of fear that a White person may just have ended up receiving a Negro's blood.
Oh, the horror! From www.essortment.com:
Because of racial segregation, the Army Navy and Red Cross had separate blood banks for blacks and whites. Because the blood had to be collected and stored separately, it was costly and time consuming. Commenting on this situation, Drew said,
"I feel that the recent ruling of the United States Army and Navy regarding the refusal of colored blood donors is an indefensible one from any point of view. As you know, there is no scientific basis for the separation of the bloods of different races except on the basis of the individual blood types or groups."