What about people who want the truth? Michael Smith for one said that he believed the Wells report until he read the Goldberg response and now he doubts a lot of it.
I think you are looking at this from a consequence standpoint rather than from an evidence or decision making standpoint.
You are saying he will look bad changing the punishment but actually he will be changing it because vital information was withheld from him. What would really look bad is ignoring that vital information.
He isn't reading it a second time and changing his mind. He is reconsidering it based upon new information that calls much of it into question. Are you saying that he was supposed to know the facts that Wells left out, or dismiss his conclusion with nothing to refute it and therefore must ignore the new information?
The analogy is that the prosecution presents a case to indict someone, they are indicted and then after the defense presents their case, you are incompetent to now think they are innocent.
This isn't only after Goldberg's response but also after a hearing. I think it is unreasonable to say that someone hearing an appeal looks incompetent by having that appeal change their opinion, especially when the accused never had a chance to state their case before the initial ruling.