This seems like it's merely codifying a practice that already existed de facto. I doubt Harvard had a specific social media monitoring policy in place when it rescinded admissions from the admits posting offensive memes, but that didn't really mean anything to the kids who got un-admitted.(1)
Not sure what to think of how big a step this is.
[1] (https://www.thecrimson.com/article/2017/6/5/2021-offers-resc...)