Possible that the barges, carrier, etc are currently empty because preps are needed, and securing large numbers of inmates is a complication if at sea. A logical sequence might be to temp house large numbers of visitors in any or all of the FEMA camps (which always did look more like detention centres more than holiday camps), and transport them in large transport planes in batches as appropriate. (Wasn't there a big bunch of transport planes on training exercise recently..?). The barges would - by then - be ready and prepped for detaining visitors, with non-seagoing staff. The aircraft carrier might be a mil security measure, against a sophisticated possible adversary which is not yet completely stitched up?