Hi Matthew. If you intend this to be binding, I suggest that you coordinate this with other work being done by WMF Community Advocacy and Legal. My hope would be to have a uniform Friendly Space Policy that is a TOS amendment and applies to all Wikimedia spaces.
A note on IRC channels: these are generally governed by Freenode with the assistance of volunteers, and not WMF. I imagine that a WMF policy that has community consensus would be enforced by IRC ops in Wikimedia-themed channels. In general, I think ops are good at keeping the peace.
Regards,
Pine