The tweet very specifically says "the people who live in or work in or ...", it's not singling out just workers at all! You're arguing a completely different point.
Also, how the fuck do we know what the people in-frame are? By what metric did we determine that they're "culture afficionados" and not workers? They're not actively swinging hammers in the image?
And what's wrong with artists anyway, socialist countries obviously had plenty of those??
And, even if they were workers, they probably wouldn't be the ones who built it anyway! Construction is its own separate sector of the economy, most workers in socialist countries aren't in construction and thus live in homes they didn't build themselves, like, what are we even talking about here?