The link given in the Twitter post is a link to a WordPress blog. The blog post said :
You Asked – And You Shall Recieve #DHS Emails – *all emails and files were obtained legally. -
The article shows a Mediafire link download link with a PDF file ogc ap redacted foia process 301 350.pdf (8.04 MB) , in which the e-mails are capsuled in.
As Anonymous Said that, They got this File in Legal Way, We try to find out and Get that this PDF is available on the DHS site at https://www.dhs.gov/xlibrary/assets/foia/ogc_ap_redacted_foia_process_301-350.pdf and https://www.dhs.gov/xlibrary/assets/foia/ogc_ap_redacted_foia_process_651-700.pdf
Easy to find such File using Google Dork: site:dhs.gov/xlibrary filetype:pdf foia . Thats why this should be consider as any Leak. This may be Developers mistake that they DHS allow bots to index such information on search Engines.