In fact, it's much more like the attorney is paid, which is considered fine in courts. Indeed, having contributors who are potentially biased, but who each argue their point and agree to a method of conflict resolution, is considered one of the most powerful methods of seeking truth. It's also used in academics, where each researcher bring their own biases to the table.
> Any paid, undisclosed influence is wrong, period.
I guess you didn't read the article? The paid influence was disclosed.