Background reports like these, along with drug testing for office jobs that don't deal with heavy machinery, are indicative of companies that have unhealthy views of the employer-employee relationship, especially in a country with at-will employment. Steer clear of them.
That is to say: Sometimes companies don't have much choice in some of this.
EDIT: I just remembered that I was talking to my corporate attorney's office recently (medium-size-law), and they say that if any applicant's facebook page over spring-break was too salacious (for example), they wouldn't be willing to hire them, because they didn't want the client to think that they were not 'conservative and judicious and considered' (when I say 'conservative' here, it has nothing to do with left-/right- wing politics in the US)
Employees in a client-facing role have the potential to harm a company badly. Companies are cautious. Now, I believe this twitter thing in the OP is ridiculous, and their faulty use of NLP is beyond atrocious, I think that it is fair for employers to be concerned about linking their reputation to that of "proven" rogues, renegades (I can't even spell renegade, George), party-animals, and revolutionaries.
Do you disagree?
Not at all. I understand that drug testing is required due to contractual obligations and things like security clearances. However, I choose not to apply to such jobs because what I do on my own time doesn't need scrutiny from my employer. I've heard from colleagues of companies in the consumer app space sometimes requiring drug tests for their engineering and non-engineering roles, which is more of what I'm addressing. There just isn't need for that beyond an employer or HR department not liking the idea of someone smoking a joint on the weekends.
People who choose to allow their public online presence to be unprofessional are allowed to be scrutinized by those who care about those things. However, if your employer is hiring companies that use bots to friend your private profiles and mine content from them, that's an overstep in my opinion. Wanting a dossier on an applicant's likes, opinions and a sentiment analysis on their posts is kind of absurd in my opinion.
For one - I haven't thought through the ins-and-outs of this very well yet.
But in this new world, I may need to. I may come back with some questions, as you seem to be quite sensible! :-)
(BTW, IMHO: Bots to friend and mine is clearly over the line)
for the same reason that i object to the public ostracising companies because one of their employees dared to have a personal opinion that is different from theirs.
as long as an employee is not using the company as a vehicle for their personal agenda, its not fair to demand that the company distance themselves from that employee.
in the same vein i expect that companies do not screen candidates for their private opinions.
this kind of screening only leads to a defacto restriction on the freedom of speech.
when sharing my opinion restricts my ability to get a job then i have no freedom of speech.