x86 is a commodity. It's not interesting—"Oh, boy, another cheap x86 computer . . . haven't seen that before." Building an x86 something or other is old news. It's been done to death and nobody really cares anymore. ARM on the other hand. In this in this sort of performance bracket? It's is new and exciting. It hasn't been done to death. It's fast, low power, and interesting.
Besides, since it's a pocketable server that seems to be being outlined here, it's gonna run off a battery and x86 is a major handicap for that sort of usage.