Is the difference in the latter case just that someone clicks "ok, post this"? I don't think that a quality-review (or lesser, a mechanism to queue and release content to the site slowly over time) turns user-generated-content into site-generated-content.
If Youtube did a quality review, it would still be UGC.
If Youtube did a post-facto quality review (to remove copyrighted music), it would still be UGC. ...
Not honoring takedown requests is a different matter, and just sounds like a dumb call.