That was my initial thought, but then I read the article.
DOJ does have that footage. But online sleuths have proven to be an extremely valuable resource in identifying Jan. 6 participants, using the CCTV footage to determine which rioters entered the building and then building a database with the clearest photos of those suspects. They have often used facial recognition for leads and have aided in hundreds of cases against Jan. 6 defendants.
Blurring the footage isn’t the empty gesture I thought it was. All he’s doing is exposing the layout of the building while protecting insurrectionists. Bear in mind that the building was deliberately designed in a confusing way for security purposes.