Safe Mode is not recommended for use with zenphoto, thus it may not be prudent to consider it a "bug" in the zenphoto code, as Safe Mode is not realistic for proper PHP server operation. This is a snippet from a post that the developer, Tristan, mentioned a while back (and I quote):
1. Contact your host and tell them you want Safe Mode disabled, and point them to the following site: http://www.php.net/manual/en/features.safe-mode.php
2. PHP with Safe Mode on is basically debilitated, so I wouldn't pay for it if I had a choice. It is of course up to you though.
But I'll leave that up to Tristan to ultimately decide, but I gather from his previous posts that he is not entirely happy about safe_mode on the webserver where zenphoto is installed.