It is the sole responsibility of plugin developers to ensure all files within their plugins comply with the guidelines. Intentionally writing code to circumvent guidelines, or restoring code they were asked to remove, is prohibited (see #9 illegal/dishonest actions).
Developers are expected to confirm, before uploading to SVN, the licensing of all included files, from original source code to images and libraries. In addition, they must comply to the terms of use for all third party services and APIs utilized by their plugins. If there is no way to validate the licensing of a library or the terms of an API, then they cannot be used.