How is Mrs.Johnson a threat to black people?

She believes that black people should simply accept what they're given and not aspire to be more. She scoffs at progression and warns the Youngers to stay where they are.

Actually, there is a more specific answer to this question then what Jill d said

Mrs. Johnson THREATENED the Youngers by showing them a newspaper of a black family that moved into a white neighborhood and how they were bombed.By doing this she is specifically THREATENING the Youngers by telling them that this might happen to you if you move into Clybourne Park. She believes that blacks should stay in their position and shouldn't' "push it" meaning they shouldn't try to replicate a better life like the whites. Though, she also seems to be jealous of the Youngers at the same time.

Mrs. Johnson threatened the youngers.

Every one is copying Joe for the source part, so STOP it's not cool, come up with ur own thing.

Emily ur a stupid ass