College admissions is already an essentially dehumanizing process. The admissions office doesn't care about you as a person, your individual future, or your education. It wants to select the people who already, independent of where they go, have the highest chance of being successful, and of enhancing or maintaining the prestige and overall reputation of the university. There are some easy metrics for this. Grades. Standardized test scores. Can you put sentences and paragraphs together in a coherent manner. If you don't have those things already, they don't want you. Whether that's fair to you personally, whether you might have some excuse for the lack of those things, doesn't really enter into it.
Here's another easy metric. Are you dumb enough to get yourself caught doing dumb stuff. Yes? Then hey, that's a red flag that maybe you aren't going to help the prestige and reputation of the school. Bye.
Is this fair? Not really. It's dehumanizing, it doesn't take individual circumstances into account, it isn't nearly as meritocratic as we like to imagine. It's also hard to see a different system taking root given the incentives in play. This is what we've got.
Of course Harvard dropped these kids. It's easier to reject an applicant than rescind an admit, and it's far far easier to rescind an admit than expel someone. Of course they dropped them now before it became exponentially more difficult to do anything.
And really, given that their behavior was exposed like this, this was the best outcome these kids could expect. Their names weren't publicly released, so no one is going to chase after them on social media, nobody is going to blacklist them, they can still go to their second choice of prestigious ivy league private university.
I don't hope these kids fail. I hope they go on to learn to be decent human beings, and then have good lives in which they are kind and decent and try to help those who are less fortunate than themselves. But it's hard to see Harvard as having done anything wrong here.