The article says Quardriga didn't keep any books. They're handing over the full database they have but that info might be garbled and meaningless.
QuadrigaCX may not have kept traditional books -- that were accessible to investigators anyway -- but they obviously kept a working database of user accounts and transactions. I assume their database can be pieced together by competent analysts. That's why they made this demand:
Following that, on Feb. 26, the CRA sent EY a seven-page production demand letter. The list of requests includes financial records and documents for tax years ended in 2016 to 2018, corporate legal records, and things like the platform’s raw database, files of AWS accounts, wallet addresses, fiat transaction records from payment processors, and so on.
The company is just giving already known information from this users to a different department and even if they have found something like discrepancies in their earnings I don't think they can be used against them.
Why is the CRA demanding this data if not to use it against QuadrigaCX customers? They are a tax agency. They aren't investigating the site owners or trying to help the victims. They are here to collect tax money.