Storm should not have been left off.
Emma was portrayed as not an omega in Endsong. That is why the Phoenix was burning her up. Yet, after that the writers amped up her telepathy having her use it globally without Cerebro and going head to head with Exodus etc.
Supposedly, Emma and Betsy are Omega level telepaths which may or may not mean they are omega level mutants over all. AOA Jean unlocked Betsy's omega telepathy according to a writer.
And we have Teen Jean who they remind us all the time is an omega mutant, actually being burnt up by the Phoenix. So the idea in Endsong (which stemmed from New X-Men) that only omega psychics could truly wield and exert control of the Phoenix seems to be ignored given that fireflies, swords, and the Phoenix Five have wielded it.
Originally omega mutants were suppose to be those with unlimited potential for power. They could be global or universal threats and perhaps near immortal. Now everyone is an omega and it has lost all meaning.