It also appears that the question was posted after the test was taken. In this case there is no security issue because the exam has already been administered. If they are not giving the same exam at the same time everywhere - or at least with enough of an overlap that nobody leaves before the exam starts anywhere else - then the problem is their own broken security model. It's not academic cheating if someone who has completed the exam discusses the questions in public and since they are minors they can't even sign a contract to enforce legal penalties.
This is more or less completely not the way standardized testing works.
Standardized testing works by using current test questions and possible test questions for the future and mixing them together, scoring some and not scoring others, and relies on being able to re-use questions. That re-use is how you normalize the difficulty of exams. You agree not to discuss the questions.
The seriousness of discussing them goes up as the professionalism required goes up. Talking about Bar exam questions can be a *massive* deal. Talking about LSAT questions can be a big deal. Talking about SAT questions can be an issue that affects your college admissions prospects.
As a practical matter, a very small bit of discussion is normal, mostly just with people who took the test right after it. Good testing authorities only care if you cross the line--like describing a test question to an unfiltered audience or in an online forum or test prep book, for example. Posting a question to twitter is not okay. Posting comments that reveal something about the particular test is technically not okay, but you have to actually look at the circumstances and make a judgment call. (A lot depends on whether everyone has finished the particular test yet, for example.)
That being said, there is *also* a financial incentive for testing companies to go after people who are too egregious. Test companies license old tests and sell them as prep materials.