Unpublish Dynamic Component when Page is unpublished

We have a setup where component is dynamic and its also used on Page. But by-design in Tridion if you un-publish a Page which is using a dynamic component, it does not un-publish the component.

We have to fetch the component based on the metadata at various places and attached on page where component was also required on page for following requirements.

• Author driven Page name
• Author driven page Url
• Author driven page metadata.

so following event code was written to handle the scenario.  in our scenario 

 [TcmExtension("UnpublishEventHandler")]  
   public class UnpublishEventHandler : TcmExtension  
   {  
     public UnpublishEventHandler()  
     {  
       EventSystem.Subscribe<Page, UnPublishEventArgs>(UnpublishComponent, EventPhases.TransactionCommitted);  
     }  
     public void UnpublishComponent(Page page, UnPublishEventArgs mUnPublishEventArgs, EventPhases mEventPhases)  
     {  
       var appConfig = ConfigurationManager.OpenExeConfiguration(Assembly.GetExecutingAssembly().Location);  
       string cts = appConfig.AppSettings.Settings["UnpublishPageComponentTemplates"].Value;  
       IList<ComponentPresentation> cpList = page.ComponentPresentations;  
       List<IdentifiableObject> items = new List<IdentifiableObject>();  
       if (cpList != null)  
       {  
         foreach (ComponentPresentation cp in cpList)  
         {  
           if (cts.ToLowerInvariant().Contains(cp.ComponentTemplate.Title.ToLowerInvariant()))  
                        items.Add(cp.Component);  
         }  
         IEnumerable<IdentifiableObject> itemsenum = items;  
          List<TargetType> targets = new List<TargetType> { };  
          foreach (var pubTarget in mUnPublishEventArgs.Targets)  
          {  
            targets.Add((TargetType)pubTarget);  
          }  
          var transaction = PublishEngine.UnPublish(itemsenum, mUnPublishEventArgs.UnPublishInstruction, targets);  
       }  
     }  
   }