Your argument is basically if Jason Aaron SAYS something it is logical. That's not the definition of logical.
The explanation for the choice of Echo was that Phoenix lacks imagination and needed someone whose power is copying stuff, hence lacking even more in imagination, to carry out its path of destruction. Again. Zero logic and sense.
If the Phoenix was answering Namor, then it makes no sense that it would be 'intercepted' by whatever rando version of Khonshu Aaron is using. Aaron has the Phoenix being stronger than Thor and the gods, so it doesn't make sense that it gets stopped by MOON KNIGHT??? Mephisto has nothing to do with Phoenix 'needing' a host. Logically, if the Phoenix is answering Namor (another dumb idea which makes no sense), then logically, it should have gone to Namor, so how is 'getting released' by Moon Knight (dumbness stacked on dumbness) prompting a tournament, which is about winners and losers, not about learning about characters. The Phoenix is TELEPATHIC, it already knows about these characters. And none of these characters were willing or interested, except Namor. All these characters were randomly plucked out of the blue, with no logic except Aaron liked the characters or was pushing MCU characters. I mean, seriously, Shana and ZABU???