CRAB - consider that the fact that the aircraft in question was moving downwind at the time and losing translational effect therefore pulling more collective to maintain height.
I don't think EC would have issued an SL like this if they did not have good reason. I suspect there are a whole bunch of 'incidents' that we are unaware of. If they say don't try and fly away with this issue going on then they must have lost few to that problem.
If not LTE then what would the failure mode be? Is there a history of drive shaft failures?
Anyway, sad day for the Taiwanese CG. If there are lessons to be learned then I hope they will share them.
G.