The one thing SOU has is the train station and decent road links - BOH has neither, the airport is approached by a country lane and continues to shaft its passengers by charging them a drop off/pick up fee which is not only a rip off but obstructive in my view to airport development and easy access which imho is off putting and crass.
BOH could usurp SOU in getting rid of this drop charge.
I would say at this time with no mainline carriers at BOH that a Lounge would benefit.
Would the likes of FR and TOM pax pay for Lounge access?
Some maybe would as a treat for their Hols but I doubt it would be taken up by that many to be viable.
I would say the airport needs to sort out its infrastructure, car parks etc rather than toy with vanity projects.
Re the BOH-SSH canx flights - I recall was this was the first season to fly there from BOH to Egypt? but sadly coincided with the effects of the Revolution and the downfall of the successive MBH Govt.
Since the MetroJet crash no SSH flights from the UK at all.