It can be that they're actively looking for this to happen to set a legal precedent legalizing this.

It's not a bad argument - if you are allowed to view content in an official client, it must mean that you are licensed to view said content and that a third-party client which displays the same content should be allowed to do so since you've already got a license for it.

Adversarial interoperability is our only escape of big-tech monopolies.