HELLFIRE it is difficult to remove confidential data, and the process offers no guarantee for stripping such a large dataset of all personally identifiable information (PII), financial data, medical records, and other sensitive content. ...
Truly, data is forever - especially once it's unleashed onto a public network. Once 'out there' in whatever form, one cannot ever be truly certain they know of all the instances where it exists thereafter... hence no way to be sure they've removed all copies of it - assuming they even have a way to do remove it in the first place.