if i was in the same position as haru I would've done the same thing, i would act dumb, haru might not realize it but unconsciously he's acting as a troublemaker you know why? because he already stands out too much within the research institute so he needs to create a persona that deviates from what is expected from him.
Their sense of justice is indeed radical, virtuous even, but the problem is that they only deal with problems based on their emotional point of view and that only tackles the tip of the iceberg or surface of the problem. Their methods bring consequences that worsen the situation at hand. their views are shallow and narrow-minded.
for example slavery, indeed slavery is unsavory but as said in the manga those slaves are criminals, rather than being executed they are paying for their crimes by doing free labor which in my opinion is way better than just killing because humans aren't gods that should play with lives. so if blue justice really wanted to "free" those slaves they would just create more societal problems by releasing those criminals.
omg this is like an AU where in donggyun is an idol and the girl is a fan