This line is your problem  

    $this->getCollection()->load();

You are loading the collection and later you apply a filter in the template.  
Once you load the collection all filters and sort orders applied have no effect.  
So you should apply the filter before calling `load` or before iterating through the collection.  
In this case you should apply the filter in the block class.  

As a general case, the templates should be used only to present data, so all data manipulation should be done in the block classes.