I'd like to see cat lord's level treated in much the same way that Dfg works right now.
In dfg, until you kill Kherab, teleportation is unreliable, even with control.
After the dwarf is killed, it returns to normal.
Cat Lord level could behave in similar way - as long as Cat Lord is present, teleportation is forbidden.
Once killed or once he gives the PC his ring and disappears, teleportation should be permitted again.
This is mostly for convenience, when you're passing through the area several times and the route between staircases is particularly convoluted.