I've always treated 'Atlas of the Imperium' as definitive in terms of the location of star systems. Sector and subsector names have been a bit more problematic (e.g. Alpha Leonis vs. Alpha Crucis), as have locations of stars (e.g. Aldebaran). For sectors that didn't appear in 'Atlas of the Imperium', the usual canon requirements come into play ("did GDW print it?", "was it printed by one of the main line Traveller license holders?" "was it printed by someone with authorization from GDW?", "is it generally accepted as canon by one or more of the Traveller communities?" and so on).
In this case, Geo did a common sense thing, but it's not official and may have been generally accepted at some point by a segment of the TNE community, but as others have suggested, there are better explanations for the location of the 21 worlds and adding an entire star system probably isn't the best one.
After all, aren't subsectors and thus subsector maps a Third Imperium creation? Sure the Solomani use them, but they were once part of the Imperium. Subsector maps for places outside the Imperium and Solomani Confederation wouldn't denote any sort of administrative boundaries.
In this case, Geo did a common sense thing, but it's not official and may have been generally accepted at some point by a segment of the TNE community, but as others have suggested, there are better explanations for the location of the 21 worlds and adding an entire star system probably isn't the best one.
After all, aren't subsectors and thus subsector maps a Third Imperium creation? Sure the Solomani use them, but they were once part of the Imperium. Subsector maps for places outside the Imperium and Solomani Confederation wouldn't denote any sort of administrative boundaries.