It seems to me that the ethics board, by including a number of mainstream-politics policy folks (not just James), was an effort to look responsible in the eyes

It seems to me that the ethics board, by including a number of mainstream-politics policy folks (not just James), was an effort to look responsible in the eyes of mainstream politicians and political movements who might seek to regulate them more than an effort to actually seek ethical counsel. Other people have addressed how it seems unlikely that the board would have meaningful understanding of Google's work in the limited schedules they had and be unable to meaningfully apply oversight and produce guidance. If the whole thing was a sham, it is definitely better not to have a sham (an "ethics council" rooted in unethical behavior) than to have one. And even if it weren't deliberately deceptive, not having an ethics council that wasn't going to work and looking publicly like you have no oversight is still likely better than having one taking up the role of one and causing competitive inhibition (the way certain drugs can physically take the place of biological molecules and prevent them from functioning).