>I'm inclined to call that step very, very non-obvious.
Agreed - it's not very obvious, and kind of awkward. The first time I wanted to do this, it took a little bit of head-scratching and thinking "what if I click this button?" before I figured it out - perhaps 30 extra seconds of reflection on my part.
Thankfully, iOS is evolving rather quickly, and if this was judged a useful feature, in a future release an "email PDF" button may be added to the "Add Bookmark/Add to Reading List/Add to Home Screen/Mail Link to this Page/Tweet/Print" options that are already available directly in mobile Safari...