Two points of perhaps salient interest which have in part at least been raised before.
Was an IFR flight plan filed out of FAGM or was the positioning flight the usual VFR under the TMA story?
If you tank at FALA for an international flight, can you claim back VAT/Excise or any financial benefit on refuelling which you could not have done had you tanked for the long flight at FAGM?
Plenty of aged and experienced pilots have whacked out in SA in situations where a less experienced and perhaps younger man would have taken fright earlier on in the proceedings and either stayed put or diverted as appropriate to the particular circumstances of the day.