why not just accept the overweight landing and avoid dumping fuel?
The thought of all those tyres going bang and the aircraft sliding off he runway might have been a consideration.
I watched it on FlightRadar an it looked like he used al the runway and was stationary at the end for minute or so before going back to the apron.
I think that by not being a bit more open about the cause they are only fuelling further speculation which may be even more damaging to Boeing's tattered reputation