pass a layer to freeze it where the time indicator currently is. Pass a specific time (in seconds) to freeze somewhere else.

freezeLayerAtTime.jsx

function freezeLayerAtCurrentTime(layer, specificTime) {

    if (!layer) {
      // no layer
      return false
    };
    try{
      layer.timeRemapEnabled = true; 
      var timeRemapProp = layer("ADBE Time Remapping");
      var container = layer.containingComp || null;
      if (!container) {
        //container comp not found
        return false
      }
      var time = (specificTime && !isNaN(specificTime)) ? specificTime : container.time;
      timeRemapProp.setValueAtTime(time ,timeRemapProp.valueAtTime(time, false) );

      // remove first and last keys
      var keysAmount = timeRemapProp.numKeys;
      if (keysAmount == 3) {
        timeRemapProp.removeKey(3);
        timeRemapProp.removeKey(1);
        // Freeze Seems Successful

        return true;
      };
    }catch(e){
      // something went wrong, you could print or alert the error
    }

    return false
  }