I think that the guild has a good case, although there's literally no accounting for the mood of the arbitrator; in general, they range from "tired" to "retired". In particular, reading the contract:

• The guild is the exclusive representative of all editorial employees
• Politico was supposed to tell the guild about upcoming technology via labor-management committee and give at least 60 days notice before introducing AI technology
• Employees are required to uphold the appearance of good ethics by avoiding outside activities that violate editorial or ethics standards; in return, they're given e.g. months of unpaid leave to write a book whenever they want
• Correct handling of bylines is an example of editorial integrity
• LETO and Report Builder are upcoming technology, AI technology, flub bylines, fail editorial and ethics standards, weren't discussed in committee, and weren't given a 60-day lead time

So yeah. Unless the guild pisses off the arbitrator, there's no way that they rule against them. They're right to suppose that this agreement explicitly and repeatedly requires Politico to not only respect labor standards, but also ethics and editorial standards. Politico isn't allowed to misuse the names of employees as bylines for bogus stories; similarly, they ought not be allowed to misuse the overall name of Politico's editorial board as a byline for slop.

Bonus sneer: p46 of the agreement:

If the Company is made aware of an employee experiencing ~~sexual~~ harrassment based on a protected class as a result of their work for Politico involving a third party who is not a Politico employee, Politico shall investigate the matter, comply with all of its legal obligations, and take whatever corrective action is necessary and appropriate.

That strikethrough gives me House of Leaves vibes. What the hell happened here?