The article became increasingly redundant as it continued. The crux seems to be Google isn't their employer. These workers work for a subcontractor, Cognizant. Cognizant performs services for YouTube Music.
Cognizant is refusing to bargain citing the ongoing relevant litigation* between its employees and Google.
I'm not sure what the legal process is called for union claims.
It's redundant because there's basically a circular argument that G and C are using to not respond to the workers. Workers want to C negotiate with G on the terms of their work with G but C says they can't because they're just contracting with G. Then G says the workers can't negotiate with G because they work for C. Both companies point the finger at the other as to why they can't help and just give nothing back to the workers.
The article is confusing but it sounds like the union wants both C and G at the table, but C and G both agree that C should be the employer and G doesn't need to join the talks. So C is saying, if you really want G to join, you'll have to wait until the appeals are finished.
I'm guessing the union doesn't want to negotiate with C, have C go to G with the terms and G refuse and just causing endless delays in a game of telephone bargaining.
One idea of subcontractors is to split and delegate societal responsibility to others to appear to be clean. Surely the law is focused on Cognizant here, but the responsibility lies fully on Google, including their ability to intervene.