Are you attempting to block POST's on AEM Author or AEM Publish?
If you are trying to block POST's on AEM Author, don't 🙂 .. AEM uses POSTS and especially those handled by the Sling Default POST servlet liberally. Blocking anything that isn't a POST to a very specific URL is asking to break AEM's OOTB functionalities. You should instead, use ACLs to control what content/content trees an AEM Author can write to via the POSTs (which will result in a 403, not a 200 if the user does not have permissions to write to the target path)
If you are trying to block POST's on AEM Publish. The pattern to do this at AEM Dispatcher is:
1. Deny everything
2. Allow only POSTs for the specific paths/path-patterns you know are required for your application
3. Ensure that your content on AEM Publish is properly protected by ACLs, so any POSTs you DO allow ensure the right ppl are modifying the content.
If you are properly filtering out (DENY'ing) these POST requests at Dispatcher, you will not get a 200, but rather a 404.