Meteor controller, action dynamic query

gistfile1.js

//this is used on a toggleChild function to add or remove mongo child relationships 

//it works fine when for $pull but $addToSet doesn't ever seem to get sent to the server

if(window[Meteor.request.controller.capitalise()]["find"](query).count() == 0){
  children[child_collection_name] = child;
  modifiers['$addToSet'] = children;
  modifiers['$set'] = { client_updated: ts };
} else if (window[Meteor.request.controller.capitalise()]["find"](query).count() == 1){
  children[child_collection_name] = child;
  modifiers['$pull'] = children;
  modifiers['$set'] = { client_updated: ts };
} else {
  throw new Meteor.Error(600, 'Invalid toggleChild child count');
}

window[Meteor.request.controller.capitalise()][Meteor.request.action](query, modifiers, function(error){});

// console dumps for pull
// query: {"_id":"ccde90cb-fe57-417e-85ab-cfff80247c3e"}
// modifier: {"$pull":{"users":"6ce98c03-2fa9-48c4-8eb7-8000d104d091"},"$set"{"client_updated":"2012-08-19T18:40:31.487Z"}}

// console dumps for addToSet
// query: {"_id":"ccde90cb-fe57-417e-85ab-cfff80247c3e"}
// modifier: {"$addToSet":{"users":"753634b3-b4ac-4049-808c-052cc42d7ee3"},"$set":{"client_updated":"2012-08-19T18:43:14.534Z"}}