Here you go friend. Nice, simple explanation.
AIPT: Dave Flynn (@Dave_K_Flynn) asked if you plan to address the Fantomex-Xavier body swap from Astonishing X-Men. And X-Men but Gay (@xmenbutgay) asked if it’s assumed the body swap was fixed as a result of the same process that has been resurrecting other mutants.
Jonathan: The Xavier we saw in HOX/POX and up to X-Force #1 was the Astonishing Xavier. Post resurrection is Charles in Charles’s body. We’ve drawn him ever so slightly skinnier.
But, you know, not for long, Chuck is working out.