Yeah, the "healing" thing was just a coverup...he never really healed anybody or anything. The bird could have been animated magnetically(using the tired and scientifically false iron-in-bloodstream trick), and he didn't heal the X-Men at the end of Imperial, he simple killed the nanosentinels, and he didn't heal Xavier, he relocated the nanosentinels from his bloodstream to his spinal cord, fusing it(until he later disabled them). Also, after Quentin Quire ODs on Kick, and his brain cells are converting to "faster than light" energy, he begins to see through time, and says to Xavier, "what if you were wrong, what if the enemy is within" or something like that, and Xorn claims that he can't heal Quentin, but he can help him go on to his next form, and next thing you know, he's dead. Pretty convinient to shut the boy up as he mentions a threat from within.
This isn't all bad however, because "Planet X" Magneto was, to a lot of Magneto fans, a complete screw up on his character. P-X Magneto was very "off", like a generic crazy old man instead Claremont's multi-faceted Magneto. And imposter indeed.