This can be a touchy question, however a well coded website might not have the security issues so posting code does no harm...
However, if you do post the source code, some people may find errors in the code and exploit them, others will inform you right away...
I would say only allow REGISTERED users to view source code, that way you can track who has seen it.. Then if anyone does use any exploits available, you can track the ip and match it up so you know who did it.