I picked up this issue because of this thread to be honest. And it didn't hurt that I just recently read through all the Heroes Reborn stories so my interest was piqued as well. I don't see from this Avengers issue Nighthawk getting shine at T'Challa's expense. From Ridley's run from jump there was a testy relationship between T'Challa and the other Avengers, so I can see T'Challa taking care of more important matters in Wakanda than also trying to do that and chair the Avengers.
It's not like they kicked T'Challa out and put Nighthawk in his place, or Nighthawk undermined him, or even insulted T'Challa here. As for Nighthawk, I still love the Supreme Power makeover (especially that sleek black suit), but I like how Aaron is writing this character more than David F. Walker or even JMS. He seems a bit more three dimensional, even if Aaron is just having fun with his own Marvel Batman. JMS's came off a little like an "angry black man" (though to his credit, JMS juxtaposed Nighthawk against the black Blur nicely), and Walker's Nighthawk was too much of a blank slate.
I don't see Nighthawk staying with the team long. He's got a darkness, as does all of the Hero Reborn "heroes", so I imagine he'll be killed off or something before too long. Until then we get the closest thing to a Batman in Marvel in a good while, and I even like how they basically draw Batman when Nighthawk is sometimes in silhouette. With Mephisto seemingly being the next big bad, it makes more sense for Nighthawk to be part of the Avengers right now anyway (albeit they can have more than one black hero at the same time on the team, but also there's Blade on the team. Blade needs more shine than T'Challa does).