As noted above, fatalism is an uninspiring argument here. "This won't work because you can't use force against those who break the rules" is framing-by-assumption that success is either all or nothing. Success is not all-or-nothing when it comes to creating safe spaces. If you take steps and someone works very hard to break through your steps, they will probably succeed. That does not implicitly guarantee failure, especially if success is defined as "safety improved" rather than "safety guaranteed".