It may be news to you, but social media checks have been taking place at US immigration for years.
I have a lot of circus performer friends, from multiple countries, many of whom regularly attend Burning Man and other festivals. If someone enters the US looking suspicious (like the average circus performer) with performance equipment, it’s been routine to check if they work as a paid performer/teacher for ages; any suggestion that someone entering on a tourist visa does paid performance means entry is refused on suspicion of attempting to work illegally. The first person who told me about this was refused entry, kept in a cell overnight and sent back to Japan, because the immigration guy googled his name and found an advert for his classes. This was over 15 years ago. A few years later, a Canadian performer I know lost his career over it, as he had been working- legally- on cruise ships and similar, but was banned from even transiting through the US after being ‘caught’ planning to work illegally- his publically available Facebook account showed him doing paid gigs, and he had circus gear in his bag. Getting international work turned into a logistical nightmare after that and he gave up.
Since news of this got around, anyone in the circus community planning a trip to US festivals have created social media accounts under their real names, which they use to post mundane life updates, keep in touch with occasional boring relatives, and maybe throw in an update about how excited they are to go to a festival in the US and learn some new skills. Meanwhile, their main account, with all their paid performance work info, is under a stage name, as is any personal website.
Bring a cheap phone, and only look at or connect it to the account(s) set up to share under their real name. A page of normal looking posts, scroll down a bit, still the same, google the name, nothing of interest comes up, questions about their plans and eventually they get allowed through.
People have been doing this to US immigration for over a decade and it still works.
I cannot see that trying to extend a similar check to everyone single person entering the country, not just those deemed suspicious, and explicitly going back not just ‘a bit’ but for 5 years- potentially thousands and thousands of posts, on multiple sites -and relying on the person to accurately supply the contact details given how easy it is to sign up to with fake data, especially if you don’t have the equipment used to post on there with you. Plus emails. Plus phone numbers, which again, are not at all hard to acquire anonymously and simply not provide.
They’re going to check through a mindboggling amount of data, with no way to check if it’s all complete, in every language spoken on earth, to check for some vague concept, when the staff currently can’t manage to run checks on a few circus people and find their actively advertised businesses.
How are they planning on physically doing the checks? AI? How good are the databases in Chichewa?
Skimping on it and simply turning away every single person who has ever posted anything not easily understood by the person checking on the grounds that it could be bad is also something that would be crazy to attempt. It would mean every person on every plane flying from any country where translations aren’t readily available would be refused entry, including the plane crew. Do airports have space to keep that many people for even a few hours? Are literally thousands of people a day from every international airport going to get arrested? Are foriegn governments going to just sit back and accept thousands of their -presumably wealthier- citizens being detained for no crime? Are they going to try demand the info in advance and deny boarding? How far in advance? If it’s more than a few days, there’s another load of posts to check! And would the airlines accept that, or would they simply stop serving the US until the policy is dropped?
I’ll not argue that it’s an awful evil plan, and just the thought that they’re looking at doing it is certainly going to deter some tourists, but actually implementing this as annouced would rely on a level of competence so much higher than the current level it’s just unrealistic. It’s not been thought through at all.
The most likely situation is that it gets shouted around a lot then gets dropped down to ‘spot checks’, which would probably be pretty similar to those already happening. Maybe slightly dialled up.