This retcon essentially just wiped out Chris Claremont legendary Days of Future Past storyline.
If the writer didn't want Franklin to have any connection with Krakoa, he could have just said the main reason is that his parents and relatives are all humans; he chose to live with them and not on Krakoa.
One can have multiple citizenships on Earth so why not multiple citizenships on both Krakoa and USA?
That would be more acceptable than retconning him as a non-mutant.
I hope that Marvel revert Franklin, Wanda, Quicksilver status back as mutants as they were originally meant to be.