This is not necessarily a conclusion you can draw from that statement. It's possible that as the economic pie grows, workers' purchasing power increases compared to the counterfactual (a non-AI world), but their purchasing power does not increase as much as the capital owners' does.
According to data in the site and paper [0] labor income is estimated $20T for all four scenarios (including no AI) in 2030. Which means capital takes ALL of the new pie coming from AI.
Also, I am not an economist but I assume if you are not growing as much as GDP, it basically means you’re shrinking. Relatively shrinking, but since everything is relative in an economy you are actually shrinking. Table 4 in paper gives the numbers.
[0] https://www-cdn.anthropic.com/files/4zrzovbb/website/cf58f84...