Liveaboards have never been allowed on GA inland lakes, although marina managers tend to turn a blind eye to 'em because liveaboards are added security. However, if you dropped an anchor in a cove on a lake for more than week, the DNR would make you leave.
But that has nothing to do with GA coastal waters...and I haven't heard of any new rules pertaining live aboards in coastal waters.
I suspect that whoever told you that live aboards are no longer allowed in GA got his inland waters confused with coastal waters. Or, got 'em confused with a time about 15 years ago when the DNR cleaned out a bunch of floating "shanty towns" who were flushing directly overboard and even just tossing garbage overboard near the mouth of the Savannah river. Those communities made the slums of Calcutta look good by comparison!
However, if in doubt, give the GA DNR a call. They're actually pretty nice folks.
Btw...I lived in GA and kept my boats on Lake Lanier for 26 years and was also a consultant to the GA DNR.