I was an undergraduate at Yale in 2015, and I agree with @krastanov's claim that the Christakis incident was a tipping point in a much larger struggle between students and administrators. [1]
Also, I lived in Silliman College and would frequently exchange long emails (1500+ words) with Nicholas and Erika. They would always respond thoughtfully and extend an invitation to discuss further over a meal. Perhaps the Halloween note was poorly written... but anyone who actually spoke with Erika knew that student activists had distorted her message beyond recognition.