Have you checked the BES Client Logs to see why it’s not starting?
/Library/Application Support/BigFix/BES Agent/__BESData/__Global/Logs
In the past, when I’ve had trouble with the Mac OS X client starting it was because it could not reach the BigFix server. Make sure you can ping your server from the Mac. Also, make sure that the actionsite.afxm file is in the “BES Agent” folder (the same folder as __BESData is in), and that it references your server by a name that the Mac can resolve.
Back to Googleing for “BigFix Client AgentControlPanel” I found …
https://www.ibm.com/developerworks/community/forums/html/topic?id=77777777-0000-0000-0000-000014903029#77777777-0000-0000-0000-000014903310
BTW: I’m not a big Mac user myself. I know what I can find via Google.