Are you ok denying visas to students based on the contents of their social media profiles?
All that said, nobody has a "right" to come to the USA to study. It's something we allow, for a lot of good reasons, but there are doubtless a small number of people that we would not want here.
Would you be ok with that social media poster being granted entry into the country?
Do I trust the government to police opinions? No, especially when there's no accountability and appeals process.
Do I believe the overall benefits that harassment-free international travel brings to this country outweigh the costs of letting in some visitors whose views I disagree with? Yes.