The union negotiations could include in the contract that AI generated actors are not allowed when SAG is involved.
That doesn't completely stop AI, since they could try to use non union actors or no actors at all.
The issue with AI is that it is software, and software can scale very quickly. So large amounts of jobs could very quickly get automated without allowing workers and the economy to slowly adjust over time. Switchboard operator was just a single job in a single industry.
It will also lead to more consolidation of wealth since existing bussinesses stand to make great savings getting rid of people, and the AI itself is privately owned. Funny enough, this could also blow up in their face since that creates inventive for people to vote.
If you were willing to spend money, why not just get it from RH directly.