I tried to use the official WordPress app to post, and it claims the XML ROC endpoint throws a 403 error message. Strangely, I can access them XML ROC PHP file just fine, even from the exact same device. Magic. Meh, not worth tracking down the bug.
Then I tried to post via email (a feature that I do remember working once). The post showed up with only a title and no body. Very strange.
Anyway, it looks like posting to AndySocial.com will remain something I do manually at home. Like an old man.