Would it be possible that they end up causing some collateral damage: for example, its revealed that their efforts to pentrate into the systems and purging the data causes the corruption of some more mundane and sympathetic records? That would allow people to argue that they actually did something that threatened national security/civitizen's rights and privacy
Yes, good point. People’s first reaction might be, hey, if they destroyed some IRS records, it means I’m not going to get a tax bill.
Ah, but they may have destroyed records of some perfectly valid deductions and you may end up getting less of a refund and/or a letter saying you owe more!
Or worse: its revealed they hit records that showed people actually paid their tactics, and suddenly tens of thousands of people are getting letters demanding back taxes they paid but the trail of it has disappeared. THAT would create a trail of lawsuits a league long that would likely bankrupt the organization.
You know, it might be possible to combine the above with this PoD below:
POD 1: An agent spins him and cuffs him.
An FBI agent takes a dim view to some random Scientologist loon showing up to shout at him and his colleagues, so he just up and arrests the loonie, in front of the 'church' representative's entourage, who panic and make a break for it; as other FBI agents chase after them, one of the runners uses his phone to call his superiors in the church that 'the FBI is on to them!'. This causes the superiors to panic as well and send out a scrub-order to all their agents currently carrying out Operation Snow White, causing the agents to panic as well and rush to complete whatever tasks they were midway through before making their getaway: this rush-job however results in a lot of sloppiness, as they fail to destroy some records that they
were supposed to destroy - records that leave a paper trail right back to them - and destroying some records that they
weren't supposed to destroy - namely, a not-insignificant number of IRS tax records.
This sloppiness and the suspicious departure of a
great many people from government offices all around the same time tips off the FBI who were just thinking they were dealing with one loud asshole: investigating the buildings that had sudden departures of supposed employees, they find several record rooms in disarray, and after cleaning up the mess and reorganizing it for proper examination, discover a number of documents are missing pages to them - most notably the ones referring to the Church of Scientology.
The FBI also find that some IRS records are missing as well, and notify the IRS about the damage; the IRS is not amused about this news, and start their own internal investigation to see what the actual damages were to their tax records. Days later the American public gets letters in their mail informing them the loss of their tax filings means they won't be getting their tax returns on time. The public explodes in anger over the loss of their tax returns, and demand answers on why and who to blame.
The FBI, meanwhile, having opened their own investigation on the Church of Scientology thanks to the botched scrub-order, are informed by the IRS about several discrepancies in the CoS's own tax filings - discrepancies that may indicate cross-state financial crimes - and set the FBI on several leads on prominent CoS offices.
The media becomes a flurry of scandal reporting as the FBI raids Scientology's offices all over the country, and end up arresting numerous Church figures on charges of espionage and destruction of evidence. The GOP is initially opposed to this investigation, due to the CoS having given their support to Ronald Reagan's election campaign, but upon the discovery of the CoS's more insidious crimes - kidnapping, child slavery, human trafficking, brainwashing, among others - the GOP quickly changes their tune in order to salvage their chances of victory in the 1980 election, and become the most hardline supporters of the investigation.
The entire circus still ends up damaging Reagan's election campaign, as he only wins the election with a significantly smaller margin than previously predicted before the 'Snow White' Investigation began. Scientology, meanwhile, undergoes complete collapse as the FBI systematically tears the organization apart, culminating in the arrest of L. Ron Hubbard himself, and his court trial ending in his sentencing for 30 years in prison for fraud and tax evasion, among other charges.
With blood now in the water, the FBI and the rest of the Department of Justice start taking a closer look at similar organizations like the now-defunct 'Church' of Scientology, including the increasingly-popular Evangelical 'megachurches', and manage to nab a few of them for their own financial crimes as well. The rise of the megachurch is blunted as a consequence, and with that, the Republican Party's pivot to the Religious Right as well.
Scientology's downfall would have far-reaching consequences for decades to come, but among the more notable ones, is that Tom Cruise never becomes a member of the 'Church', and so his rising Hollywood career remains unblemished by his humiliation on
Oprah.