To me, this sign seems just another iteration of the "Baby On Board" window plaques that were fashionable back in the late '70s and early '80s.
Those were (in my view) another iteration of the "This Car Brakes For Animals" bumper stickers of the early to mid-1970s.
Neither was serious in the literal sense. No one was actually expected to change their behavior because they realized that a baby was in a particular car, or because the car ahead of you was driven by a person who wouldn't knowingly run down a helpless animal crossing the road.
Rather, those public announcements were really meant to convey and proclaim a sense of "specialness" to the world at large. "Give me my space because I'm special."
Implicit was the message "you are not special."
The "Safe Space" sign is (again, in my view) a continuation of that concept. It is equally vacuous, equally meaningless in any practical sense. It is simply a way for someone to proclaim to the world "I'm special, and if you want to be special too you can come to Maguire 101 and perhaps you'll meet me, but even if that doesn't work out the fact of my specialness will still live on by virtue of this message."