Orobas's entry says he is faithful, and that he will not suffer the operator to be tempted by any spirit. It is a striking claim to find in a catalogue of bound demons, and it is not unique.
Several entries make comparable promises. Vassago is of a good nature. Seere is good and indifferent. Marchosias answers truly. Amy and Foras and others are said to give true answers. The recurring formula he answereth truly appears throughout.
The insistence tells you what the anxiety was. In a tradition where a spirit is compelled rather than petitioned, the obvious risk is not harm but deception: an entity that appears, complies in form, and lies. Much of the ritual apparatus in the front of Book One addresses exactly that, the constraints, the repeated adjurations, the insistence on a spirit appearing in a fair shape and in the assigned place. And the catalogue's notes about truthfulness are the same worry expressed as a property of the individual spirit.
This is a real feature of the wider literature. The angel conversations recorded by John Dee and Edward Kelley in the 1580s return to it constantly, with Dee testing statements for consistency and worrying about false spirits impersonating true ones. The concern is structural to the whole enterprise and not peculiar to the Goetia.
It also has a consequence for how the catalogue reads. A list that has to keep certifying its own entries as honest is describing a practice in which honesty was not assumed. That is more revealing about the tradition than any individual attribute in the book, and it is the sort of detail that survives translation, recopying and a century of derivative publishing largely intact.