Renraku is still a AAA corp. Doesn't that say something after that big of a screwup? People still buy a lot of their products, and they still remain one of the greater powers. Maybe they are not quite as strong, but they are still swinging. I also thought why Renraku lost the Arcology was that they just walked away from the whole situation going dum-de dum dum dum... It suddenly became the UCAS's problem, so they had to handle it. After everything was said and done the UCAS just decided to hold onto it, even though Renraku turned around after the situation and said that they have claim to the facility.
I think that speaks highly on what the big boys can get away with. I mean how many times has AZT had the corporate court come down on them? How are they still such a major power if they keep messing up? I think the biggest problem is that if every single AAA corp has done some big screwup, then it's almost as good as saying no one has.