A foot in the door, that is all Virgin wants....
Don't you think from a marketing point it makes sense to get into a market where the main contender (SAA) is cutting back on certain routes?
To fill that gap with an airline (Virgin) that can offer low cost tickets, provide a good service and make a huge profit in the process makes a lot of economic sense to me.
Just look at Virgin Blue in Australia, going strong for 5 years...
Hopefully SAA will sit up in time and realise they are making a mistake, again...