I think the author was making the point that ribosomes are constructed of proteins.
Therefore, the obvious question - if ribosomes are the protein factory in our cells, where do (or did) the proteins that make up the ribosome organelle come from?
I know.
But he’s wrong in thinking the proteins in ribosomes make the proteins.
Ribosomes are mainly RNA.
The RNA makes the protein.
RNA catalyzes the reaction that joins the amino acids.
All the proteins of a bacterial ribosome can be carefully removed and the ribosome still catalyzes the reaction.