I don't think the RC should get into biblical interpretation. Are they going to question the beliefs of the Catholic Church for instance? If not then the WTS could claim they have been treated differently and thus unfairly
I will add that I 100% agree with Simon here. By going into scripture like this the ARC has given them a way out. Just like debating with any believer, they will (and they did) come back with, "your interpretation is wrong mine is right." The ARC can't just say, "no YOURE wrong," because this is a theological battle now. In the current world climate regarding religious beliefs nobody gets to say who is right or wrong.
The only hope that will allow these particular findings to stand is that the ARC could easily clarify their findings to explain their meaning as, "not only is there no reasonable way to conclude shunning is scriptural but it is a violation of human rights and a cruelty and cannot continue." This I think was their intention, but I think it should have been done without bringing scripture into it.