This interpretation of the decision is wrong, and I think this is also not a right interpretation of copyright and of the GPL.

However, I do think that parties receiving GPL software also have standing to sue, not just authors.

And this may also be true in the US: see for instance one of the decisions in Versata v. Ameriprise where the court considered GPL to create contractual obligations towards third party beneficiaries -- i.e. towards people receiving the code. That whole case has been settled out of courts but that's still an interesting decision (and to my knowledge, this decision had not been further contradicted by upper courts so it is still interesting).