Okay, so the patch was actually easier than I expected - after poking through the codebase and figuring out what was going on, it turns out there was just a check for public_contact() != $item['author-id'] in the code that displayed a content warning. So I just added a user-level configuration option to choose whether or not to display CWs on your own posts.

The hardest part was realizing what the problem was when the server was throwing 500 errors - I spent probably an hour trying to get it to give me any sort of debug log, only to realize that I had made not one, not two, but THREE different typos.

Now to rewrite history and destroy all traces of my mistake. :P