I guess there are very few pilots who haven't at one time or another taxied not in accordance with their taxy instructions, you see it a lot in the real world and not just in LVP's either, in most circumstances its a non event, just red faces at worst.
I have never been to Jo Burg, nor likely too unless my company fit a load of drop tanks!! but these guys made a mistake, they didn't set out to make one, but it happened and we learn best from trying to understand why and how best to prevent it happening again.
There will of course be a full BA investigation and some lessons to learn, but barring intentional gross misconduct (very unlikely) then hopefully they can continue their careers with BA, but lessons for all of us, what ever we fly
Good luck
It is true. I agree a human mistake can be experienced . It quite clear it was better to avoid this kind of situation but it may happen.