A: Hawthorne is unethical because he sold the influence to environmental interest group; there is no justification

M: Nope, he's not unethical because It's environmental interest group preventing pollution doing good to public.

Need help:

I kind of get why AC B is right but do not understand why D is wrong because how I also see the above is:

=>His gaining private benefit by selling unethical vs. His action somehow benefiting the public ethical

Can someone explain?