[chrishajer]

In the admin under Settings > General, there is a post timeout setting (“Lock post editing after”):

/bb-admin/options-general.php

The default is 60. Try setting it to -1 and see if a normal user can edit an old post. If the -1 does not work, try some insanely large number of minutes so it appears that there is no limit to editing the posts. 525600 is a year’s worth of minutes.