Might be a minor point, but - pg, could you elaborate on the distinction between "bad people" and "people behaving badly"? I read most of the "Dilution" section

Might be a minor point, but - pg, could you elaborate on the distinction between "bad people" and "people behaving badly"? I read most of the "Dilution" section as saying that bad behavior is situational (someone who flames on reddit posts intelligent comments here), except for the following blurb in the middle: "forbidding bad behavior does tend to keep away bad people". Is the implication that these "bad people" can't possibly behave any other way except badly?