Think like this, those Interpol tools are very cool, so for one side police forces working on child abuse sites can for example find images and "feed" them to the database, they will input data as "unknown" victims for the system to attempt to match the images/videos to the already known victims. On another way they can feed data to the database to make matches and they can even supply ony for example MD5 hash of a file, meaning if for some reason they don't want for people to see a specific image of abuse they will "convert" it intro a unique "hash" so that others with the image can do the same and compare "hashes". When a child goes missing they add victim to the database as well, NOT as a child abuse image but as a "victim". They add photos provided by parents/family. This is used to compare with already entered data of non-id children under abuse.
In other words ALL pictures on the database that were collected for example from darkweb sites that were "busted" or even just "crawled" by Interpol teams will be "compared" by techniques of image matching with photos of missing children and sometimes even age progressed over diferent evolution conditions, etc ...
When they open a missing child entrie they will put the name of the child and all known photos for that child before abduction. Even "fakes". Meaning that they would open and entrie for MM, place there initial photos provided by parents and all found diferent photos on the net. This would include the single picture of CB with MM even if not sexual in nature. This would include photoshoped "jokes" found on the net, everything.... It doesn't need to be sexual content when added as missing victim. The "victim" is already assumed to be victim because it's missing, unlike someone that is considered victim because it's under abuse.