It is too much to expect people to moderate their bladders, etc, for close to 7 hours, let alone sit within nose range of a backwardly malfunctioning closet. If this story is true, then CO deserve every drop of effluent that will no doubt be thrown their way.
There are other questions here too. Like, why, if they conducted maintenance to the toilets on the ground in Shannon, was there still sufficient sewage in the system to over flow "just after takeoff"? Were they really conducting maintenance, or just going through the motions?