1. OP knows very well that less balance = more vulnerable = better Defence
so it's to his benefit not to fully demonstrate his 'real' capabilities. It's as if to convict, the State alleges the accused lifted 75kg but the accused demonstrates that the most he can lift is 50kg
how does one go about disproving the physical capabilities displayed by the accused ?
impossible task.
2. Someone a while back had posted a video of OP as a child running around and playing.
3. OP has a lot more balance when he is moving rapidly than when he is moving slowly or standing still
as stated by Dr.D it would be indeed quite difficult for OP to balance himself and remain perfectly still on a shifting platform scale without holding on to anything
this is static balance which is much more difficult than dynamic balance... therefore, slowly stalking an intruder would be far more difficult for OP than simply fleeing.
4. OP had a gun whether fighting or fleeing
OP would surely have been less vulnerable fleeing with a gun than confronting an unknown threat with a gun.
5. OP had Reeva, a fully abled person, to assist him should the need arise.
6. OP has less balance and therefore is more vulnerable in the dark
OP shouted at the intruders to get out and for Reeva to call the police
OP was therefore not concerned with keeping his and Reeva's presence hidden from the intruders
in fact, the only reason OP would scream these things is to alert the intruder of his presence and awareness of their presence so as to encourage them to flee
turning on a light would have taken 2 seconds, would have reinforced his message to the intruders and would made OP less vulnerable by giving him greater balance and greater mobility
yet OP chose to confront an unknown threat in pitch darkness.
This list could go on
but I'm tired