The problem with the word "nonviable" is it can mean so many different things. This thread here illustrates that point quite succinctly. It really depends on the individual on how to interpret it. It could very well be as Xenomrph and cliffhanger says and the Derelict was a nonviable source due to restrictions placed on the Auriga. It could also very well be that like others have said, the Derelict was a nonviable source due to the eggs being sterile. The CMTM page excerpt is just vague enough to support the theory that the eggs were sterile. After all, only two specimens gathered out of the entire ship? After everything Wey-Yu went through to get their hands on those eggs, why stop with just two specimens? Why not bring back as many as they can safely can or even set up a research facility on-site ala Aliens: CM?
In the end, the interpretation depends on the needs of the person interpreting the word. I want Alien 5, so for me, I interpret the word to mean the Derelict was a nonviable source due to restrictions placed on the Auriga. It serves my agenda and desire to see an Alien 5 someday so it works for me. But I'm certainly not going to deny the possibility that the Derelict was a nonviable source due to the eggs being sterile. In the end, it depends on the individual and whoever ends up writing the story for the next movie in the Alien series. That person will have their own agenda and desires and if this question needs to be addressed, it will fall to that person's interpretation and agenda.