The focus on AI is just to capture some of the current zeitgeist. Socialists generally think that most large businesses be run for the public benefit in some form or another.

This is basically making that point with AI companies as their true influence is rapidly increasing. The rhetorical strategy here is to hook socialist ideas onto something people are already thinking about, a land-and-expand rhetorical strategy.

Personally I'm against the proposal, but the details are not the point because it's not going happen in this form. It's about changing minds first, then changing policy down the road.