Discourse (Ember.js?) issue using document.write

Having a problem getting my adserver working on Discourse via it's Ad Plugin. The script is called via link to the adserver's index.php file which generates the text below. However even though this text is in Discourse's encoded data for the page build it doesn't display. The same script call put into the themes </body> area works (just down at the bottom of the forum. But that part of the page HTML is not encoded, so I am guessing this is an Ember.js issue?

Here is the adserver output.

document.write('<div class="banner" style="width:728px;height:90px;overflow:hidden;margin-bottom:3px;"><a href="https://adserver.site.net/index.php?section=click&action=875"><img src="https://adserver.site.net/banners/L112320.jpg" class="adimage"></a></div>');

Anyone have any ideas how this can be worked around? I do have root access for the server but I have zero experience with Ruby or Ember. I can change the output of the adserver script if there is a better way, etc.

Thanks!