Brunswick is a pretty upscale town and the station serves a good deal of the mid-coast...so I'm not sure how changing the city of license is good marketing practice.
I think in this situation it's more likely because of Section 73.1125 (a):
A Main Studio must be located either:
1. within a station's principal community contour
2. within the contour of any other broadcast station licensed to its community
3. within 25 miles of the center of its community
I believe, from a purely geographic view, 1 City Center was just close enough to work under those rules. I'm fairly certain 420 Western Ave, SoPO is not close enough...
Another theory (and I'm not sure on this)...but I think its possible Citadel was using 'CLZ's old digs in Brunswick as the main studio (Out on a limb on that last suggestion--but I've seen that pulled off before). I have heard those digs have been closed down and will be (have been?) demolished.