It is certainly a bug. I fear Admin Console has a few bugs that are specific to Safari.
It's not a high priority for us at the moment but I'll certainly make sure it is logged.
For now, I recommend you use a different HTML5 enabled browser [kind of hard to find a modern one that does not support HTML5 but people seem to manage it:)]. I personally use Firefox and Chromium, both work correctly with the Admin Console.
Thanks for reporting it and of course, since we're open sourced, if you'd like to investigate the issue, fix it and submit a pull request, we'd be most happy to review it.