You need the count -1 on the target_scriptrunner, not the trigger_multiple. That should fix it.
Also, a better practice would be to avoid target_scriptrunner altogether for this. Just add a useScript to the trigger_multiple, and you'll get your infinite uses and save a few entities in the process.
Edit: I've found that func_door is a lot more useful for scripted elevators. Func_static doesn't have a lot of extra utility to it.
Also, instead of ref_tag, you can use a move block in