Because they are part of the Jewish people. When Herzl said we are "A People, One People", he did not distingush between liberals, Orthodox, Chassidim, seculars, saints, sinners, or the great middle ground that most of inhabit from day to day. To say that the ones we don't agree with should be treated like pariahs is arrogance. It says that "We" know so much more than "They", and "We" are so much better than "Them" that we can disregard them as part of our people. It also says that "We" can project our people's flaws on "Them", and as a result, "We" as a people are flawless. I totally agree with you that one should not permit settlers from fulfiling their illiberal and inhumane dreams, but you are kidding yourself if you think they are not part of us. You are also presuming to have the mind of God in assumimg that "We" are completely right in every respect, and "They" are completely wrong in every respect. Life is rarely that simple or clear cut. I don't see how you tikkun olam by turning people with whom you strongly and justly disagree into pariahs. Being firm in the right, not being firmly self rightious, promotes tikkun olam.
Key U.S. House Democrat cites troublesome issues in Iran nuclear deal (Reuters)