What Mr. Rolfes is saying is that “Roman” Catholic is the title referring specifically for those Catholics of the Latin Church, not the Eastern Catholic Churches (Byzantine, Maronite, etc.).
Both Roman Catholics and Eastern Catholics are together (and equal) parts of the Catholic Church, which we believe is headed by Jesus Christ and vicariously currently through HH Pope Benedict XVI. But we Latins are also under the pope not only as pope but as patriarch as well, just like the pope also heads the Archdiocese of Rome, whereas Eastern Catholics have patriarchs, major archbishops, etc.
Eastern Orthodox are not referred in Catholic canon law as “Catholic”, just like we Catholics are not referred by the EO as “orthodox”, though we claim our Catholic Church to have orthodox (true) faith and they claim the Orthodox Church to be “catholic”.