I don't understand the rationale of Phil's question. Would Adam have some idea of changes in Nathan that we did not see throughout the year? ...

Duhhh ... I think it is a reasonable premise that compared to fans like us who see Nathan for the most part only in competition, someone who has trained with Nathan for several years could indeed have a different perspective on and/or extra insight into this season's changes in Nathan. YMMV.
[ETA: Speaking for myself, I don't think I am alone among fans in not knowing a lot about juniors in general. I had relatively little awareness of Nathan until last season, whereas Adam and Nathan have been training together for quite a few years.]
In his announcement at the top of the call, Adam spoke proudly (justifiably proudly) of being a "professional" skater (with a wry aside to acknowledge that professional skaters technically still are amateurs).
I like Adam a lot, and my heart goes out to him that he is injured. When I had the pleasure of meeting him in person, I indeed was very favorably impressed by his professionalism in many respects.
It was Adam's prerogative to dislike Hersh's question and to not want to address it, but even so, I feel that in this case, Adam (even with his very recent and season-ending injury) could have responded with greater professionalism than he did. YMMV.
Regardless of that opinion: As I said before, I regret -- for Adam's sake -- that he missed the opportunity to do himself a favor and give reporters a good quote to help keep him in the conversation as others go forward without him to compete for the U.S. title and for spots on the World team (and as a team at Worlds, for the number of slots at the Olympics and 2018 Worlds).
ETA:
... ... Phil's narrative that Nathan is the only US male skater worth paying attention to ....
If there were truth to your opinion that Phil's narrative is that Nathan is the only U.S. man worth paying attention to, why did Phil in fact live-tweet five times (more than any other reporter on the call) to report on Adam's announcement of his injury?