That's not necessarily the case. It means there could be other reasons for overriding the scale.
For example, it's an initial placement. One needs to realize that, upon admission, they might not have a lot of criminal history, but there could be factors that might raise the security level. A good example would be gang affiliation. It isn't really sensitive to that aspect, but if other information came to the awareness of a parole officer, they might recommend a higher level of custody than what the custody rating scale would say.