Hold on a second. Iyer didn't couch his statement about the importance of Coleman in absolute terms. It was a reference to how much Coleman meant to Iyer, not an attempt to diminish the importance of Coltrane.
Look at the quote:
Vijay Iyer, who once declared in JazzTimes magazine that Mr. Coleman was, for him, as important a figure as John Coltrane, someone who “has contributed an equal amount to the history of the music.”
I don't have any problem with that statement because he's seems to be making it from a personal point of view, not as some sort of music historian.