Files aren't permanently saved

I'm using this module for education purpose and I received a bug report that the reviewers couldn't open up the files. After some digging into the code I noticed that the files are only uploaded with the temporary status, meaning that a all uploaded files are removed during a cron run.

The following line in the development code suggest that this simply hasn't been ported over from the Drupal 6 version:
line 244 //file_set_status($file, FILE_STATUS_PERMANENT);

Is there a specific reason behind the fact that the files are only uploaded with the temporary status or is this a bug?

Attached to this post is a patch with a fix to permanently save the files into the Drupal database.