It appears your underlined citation refers only to cases appealed from an inferior court.
In all Cases affecting Ambassadors, other public Ministers and Consuls, and those in which a State shall be Party, the supreme Court shall have original Jurisdiction. In all the other Cases before mentioned, the supreme Court shall have appellate Jurisdiction, both as to Law and Fact, with such Exceptions, and under such Regulations as the Congress shall make.
The portion before the bold refers to the areas where the SC has original jurisdiction. The bold portion refers to the other cases previously mentioned - in Clause 1. The SC can have either original jurisdiction or appelate jurisdiction. Since this area is not mentioned in the area concerning original jurisdiction, it must be covered under the portion relating to appelate jurisdiction.
One would think that the SC cannot just reach out and hear the case without establishing its original jurisdictional claim.