Good heavens, I remember reading this when it first came out. *25 years ago*
Ahem. Anyway, as far as "it's a coincidence," that didn't seem plausible even then. That may be what Claremont intended but it's too much of a coincidence to be believable, and even then had the feel of the writer deliberately messing with the reader's head for kicks (as opposed to messing with the reader's head for the sake of an interesting plot direction or something).
I actually read Uncanny starting with #169, so for me Dark Phoenix was "ancient history" (although relatively speaking it wasn't that long prior to all of this...).
If something similar happened today it might be a refreshing change from the usual IT WAS A CONSPIRACY ALL ALONG HAHAHA... but that sort of continuity-raping MESS wasn't nearly as common back in those days (although again, this may be from the perspective of someone who'd just gotten into comics at the time). E.g., we didn't have yearly EVERYTHING YOU KNOW ABOUT WOLVERINE IS WRONG DUE TO MINDWIPES AND PLEASE IGNORE PREVIOUS STORYLINES WHICH CONTRADICT THIS.
And I realize that I am commenting on a three-month-old thread. I just recently discovered new!scans_daily and am going through archives...