The steel already has enough vacation tan
As far as I know, that is OK as long as the concrete of the base slab seals everything AIR-TIGHT.
The company has a pretty good reputation, so I just assume that everything is fine.
I found the implementation of the "formwork" for the individual foundation of the column using the rings much more interesting. They probably just pour concrete in there and save themselves the elaborate formwork.
Regards
Markus