So we are going from Cape Town to Frankfurt and I would guess that this would be about a 13-hour flight. Certainly, the aircraft would be pretty heavy.
Now then, Perf A assumes that the gear is retracted as soon as we get to PRGU (Positive Rate Gear Up).
If the gear cannot be retracted because the pins have been left in and then engines start to fail then we are completely outwith Perf A and the only way left is probably down.
It is hard to believe that anyone can manage to get airborne in this day and age without physically seeing the pins, but, having got into this position, it is entirely appropriate to dump fuel immediately in order to avoid an even bigger possible disaster.
Taking tea and biscuits with the Chief Pilot is infinitely preferable to making a big hole in the ground or a huge splash the ocean.
In any event, a return for landing was inevitable for there was no way that the flight to Frankfurt was still possible. Dumping fuel would have been necessary in order to get down to landing weight.