The article is correct... Interstellar nanoprobes are not an option
It boils down to radiation dose and self repair. The intelligence on the interstellar probe must limit its exposure to Galactic Cosmic Rays (GCR) either by minizing transit time, radiation shielding, extreme redundancy or self repair. All of those parameters improve as the vehicle scales up in size. Nanoprobes are not an option. Almost by definition, starships need to be really big.
Gary