Instead of typing {% and selecting dj_for_empty, try typing dj_ and then auto-completing. It will behave the way you expect in that case.
BOTTOM-LINE: You auto-complete the templates into the editor based on the template name, not based on the template contents.
It appears that autocompletion has two sources: regular HTML tags (for which I can't find the definitions to change anywhere in Eclipse, sorry) and the templates themselves (which you correctly demonstrated in your comment with the screenshot).
Look at this image:
Instead of typing <t and triggering auto-complete, I typed t. You can see that there are entries with <> - indicating these are autocompletions based on the actual HTML tag - and entries with # - indicating these are autocompletions based on a template.
It appears templates are to be accessed by the name of the template. Notice that the template named table provides a complete <table> and not just the <table></table> that is autocompleted if you just type <tab and autocompletes.