I can think of 2 reasons why some of the models scenes were taken down and others are still available.
1. If the staff didn't confirm the IDs for the solo and only remembered to get them for later scenes, then they wouldn't be able to show the Solo.
If they kept the solo on the site thinking that the ID confirmation that they got later on could be retroactively applied, then it could be discovered that they were distributing porn without knowing how old people were and only found out later.
2. They might have kept only messy records on the usc 2257 documents. These document need to be done for every scene you do and they cant be created after the fact. If they don't have it, the scenes can't be legally shown.
