This is the bell-ringer isn't it? He was eighth. But he was injured. He was injured all last season. Every single placement he had was below expectations & his potential. If you make the decision based on last year's results, you get "stay-junior." If you make that decision based on what he can do and what he is doing, he is competitive with the U.S. senior field. In fact, if we take a look--not at what we think will happen with our rose-colored glasses--but at what actually happened in the men's event last season (et hem--Cup of China & TEB), a young less than polished guy with great jumps won two Grand Prix events & made the final. A guy who only had one Grand Prix event defeated the Olympic Gold Medalist and won NHK.
Historically, having a good run in the junior ranks generally sets you up well for success in seniors if you can maintain that momentum.
We saw Uno's success on the JGP last year lead to a 2nd place at senior JPN Nats, 5th place at 4CC (which was an amazing event, his overall score was really high), and a JW title.
Josh Farris did well in juniors during the 2012-2013 season and wound up placing 4th at Nationals and winning JW. He was a respectable 5th at his first GP where he beat Jeremy Abbott and was a contender for the Olympic team before he got injured. He still wound up having a solid nationals and showing at 4CCs later that season, anyways, and built on that this past season.
Dornbush competed on the JGP in 2011 and wound up 2nd at Nationals and made the senior World team where he was 9th and the highest placing American.
Jason Brown wound up making the Olympic team 1 season out of juniors, and that was with a 2012-2013 season where he didn't medal at the JGPF or Nationals and was beat out for the JW title.
Kovtun won the JGPF that season and then placed 5th at Euros and probably could have done well at Worlds if he had skated like he did the rest of that season (he wound up making the GPF and placing 4th at Worlds the following season, regardless).
Han Yan won JW in 2012 and then competed on the JGP again the following season, he didn't even make the JGPF but still went on to place 2nd at 4CCs that season and really should have been sent to senior Worlds.
So basically, if Nathan can do well on the JGP this season, he's setting himself up well. Ideally, he wants to go to senior Worlds I'm sure, and he still could, but in the event he doesn't make that team, he'd go into JW a favorite and accustomed to the junior length programs. Competing as a senior internationally last season, not having the best results, then coming back to JW didn't turn out so well for Pitkeev, so where Nathan is only 16 (the same age as Pitkeev last year), I don't think going full senior right now will really help him.
Nam is a bit of a different situation because he had already competed at Worlds at 15, was a shoo-in to make the World team given the Canadian field, and had the JW win and having Orser as a coach help increase his stock heading into last season. Additionally, while he did well all last season, his improvement was gradual and he wasn't exactly getting super scores (especially where PCS is concerned) early on last season. He wound up placing 5th at Worlds because he skated great there and had improved a lot over the course of the season. Nathan's situation is very different so I don't think Nam is the best comparison.