I thought intellectual “Safe Space” was more about having a space in which people are shielded from other people expressing themselves freely in ways that might require defense or stir objection. So, the opposite of this. At least, that is what is being demanded nationwide, and that is what the Dean is responding to. Maybe the letter is too preemptive of a strike, if you haven’t experienced those demands on campus yet. But it’s reasonable that the incoming class of 2020 is more familiar with this concept, based on the context of public discourse broadly among students today.