As I understand it, the new user restrictions are in place to reduce spam, not to prevent porn (though that is also desirable).
Rather than making a whole new feature just for images from new users, how about changing the behavior of the existing feature?
Currently, the new user restrictions are revealed to the user through a banner stating that they can't do that. The user has to remove the content before being allowed to post the question or answer. This leads to good users with good questions linking to images on other hosts instead of attaching them via the image uploader, obfuscating URLs, and asking for edits. Then, editors like Blender need to come in, upload the links, un-obfuscate the URLs, and then the post is ready. Hopefully, it hasn't attracted downvotes for the formatting yet. This does limit some spam, but is less than ideal.
Instead of this mechanism, how about stripping the restricted content from the post, and suggesting an edit with the diff? This would not only ease the task of the editors but also allow new users to post great first questions and answers.
The current "Your suggested edit will not be visible to others until it is approved" banner could be amended to "Your [link[s]] [and] [image[s]] will not be visible to others until [they are|it is] approved" for this system.