Wikipedia says the Intel ME has been an x86 since Skylake (2015), and before that it was ARC not ARM. AMD is the one using an ARM core for that functionality.
More than a bit, Intel actually produced ARM processors for a decade. The XScale line of processors was sold to Marvell in 2006, and that knowledge has probably atrophied since then. Intel used to build their network interface cards around an XScale core, not sure what they're using now.
