I'm not sure I understand your point. You seem to be saying Hoover was somewhat justified in infiltrating Black organizations and labeling Black leaders and groups as Communists because some individuals and groups were listening to the approaches of Communist groups. Other Black people/groups like the NAACP were doing all they could to distance themselves from the Communists.

Should the Scottsboro Boys have turned down their help when every agency of government, including the courts and law enforcement, was railroading them? The same FBI under Hoover hid evidence that Sheriff Willis V. McCall murdered one man and shot another when transporting them for retrial in the Groveland Four cases.

Yes, people were afraid of Communism, one could say they were made to feel that way by McCarthy and others to protect their own interests. If I were living in that era, I'd have listened to the Communists as I knew what to expect from America at the time.