The Abbott infant formula plant situation is basically an absence of evidence situation rather than an evidence of absence situation as there was limited testing and the inspection occurred 5+ months after the infections.
One of the strains from one of the tested sick kids matched a strain found in an open formula container, but that strain doesn't match any of the five found from the FDA inspection.
I don't know if it will be resolved either way at this point. Cronobacter infections aren't reportable diseases, so investigations and genetic sequencing don't start immediately when outbreaks occur.
But the plant has a lot of quality control and contamination issues. One closed container of formula was contaminated with Cronobacter but was caught before it left the plant. So there is evidence of both plant contamination with Cronobacter and evidence that such contamination can get into the formula produced before it leaves the plant.
Even without definitive evidence tying it to these sick children, the plant was not functioning safely and had all the failures necessary to cause a Cronobacter outbreak.