Nothing places Honorius of Thebes anywhere outside the texts that name him. There is no notice in any chronicle, no document, no independent mention of such a person. The atlas keeps the entry because the attribution is a historical object with a traceable career, not because the man behind it can be established.
Two claims were being made by the name. Thebes tied the work to Egypt, which medieval Europe took to be the source of the oldest and deepest learning, and making the author a son of Euclid tied it to geometry, the discipline that in the same period stood for knowledge which compels assent. An anonymous compilation carrying that pedigree is no longer anonymous and no longer new. The device was standard in this literature, which claims Solomon, Moses, Adam and Hermes with the same confidence and on the same evidence.
The name then had a second life. From the seventeenth century a quite different book circulated as the Grimoire of Pope Honorius, framed as though issued by a pope and trading on confusion with Honorius III, and it became one of the most widely printed magical texts of the following two centuries. The two works are not the same and are not by the same hand. Their shared name is a clean illustration of how authority was manufactured here, by attaching a text to a figure in no position to object.