The IRS gets it as the brokerages send them your 1099 forms.
However the IRS has strict limitations on what it can use those forms for, largely they cannot share that with generic prosecutions and can only use it for tax and tax prosecutions. Plus they're under a pretty strict obligation to not share that info like the article claims the SEC will do with the CAT.
Tangental thought: But what is Intuit obligated to do with the information and how are they required to protect it, once you give them your 1099s?
Given the state of PII protection laws in the US I'd wager not much legally and they may be open to access by the police under the same old "abandoned" files precedents that give police so much access to your email and other files stored with third parties. That's all speculation though.
Those forms only include proceeds from sales. They don't include an itemized accounting of your holdings.
The SEC relies on brokerages snitching on their customers for further review (aka rubber stamped emergency asset freeze by SEC employed judges)
I assumed that avenue would be a subpoena or a warrant.