"But he notes that while anonymous speech made by Americans is protected under the Constitution, 'courts have been inconsistent in applying that protection against civil subpoenas aimed at identifying anonymous internet users.' In the case Dendrite International, Inc. v. Doe No. 3, for example, an appellate court held that a company was not allowed to unmask users who had criticized the company on a Yahoo message board."
What the article makes out to be an "unprecedented overreach" is actually a fairly subtle balancing of several different concerns. The first, and overriding, concern is that a litigant has the right to any evidence that might prove his case. Balanced against that is the concern that discovery could "chill" protected anonymous speech. Implicated in that second point is two issues: 1) most of the subjects of the subpoena do not seem to be Americans who can raise the 1st Amendment issue in the first place; and 2) 1st amendment concerns are weakened by the fact that any "chilling effect" would be the result of actions by a non-state actor (Chevron) who isn't bound by the 1st amendment.
The fact that we hate Chevron shouldn't blind us to the facts of the case. Chevron is fighting a $19 billion judgment against them. They have a colorable claim that they are the victims of an extortion scheme. It is the judge's job to figure out how to get them the evidence they need to prove their claim while not trampling on any Americans' rights in the process. They have a right to get that evidence to the extent that it is possible.