I would imagine that the Port of Southampton would stand to benefit from any Freeport status. Freeport status tends to lend itself to freight and logistics not short-haul passenger transport unless it's super time-sensitive belly-hold cargo. Could be some side-effect business travel demand but who is to say how much? Did the Freeport status benefit SOU prior to 2012?
SOU is very fortunate to be in a position to nurture further BA Cityflyer development and to attract new in-bound business & global connecting traffic from the likes of other new airlines like Lufthansa, Aer Lingus (Dublin), Air France, KLM frequency & aircraft size increases etc etc. The runway extension will unlock these airlines in terms of removing existing payload penalties.