Yes, the author of the article makes the mistake of... not listening to or responding to what the other side thinks, just because she disagrees with them. No concern was addressed in her article.
For what it's worth I have actually listened to the arguments that the other side had made, but I didn't want to focus on that in place of the stuff that I felt was missed.
I think the Go developers argued for it very well, but there is a reason they decided to go with opt-out, so calling it a mistake makes no sense to me unless you address that reason.
My argument in TFA is that going opt-in biases the data so much that it makes the process of building that system a mistake. Of course, under the assumption that it is ethically correct to build such a system in the first place.