Completely off-topic, but: I think the state of the art in castle design (pre modern explosives anyway) was a star/bastion[1], since that allowed defenders to have overlapping firezones, especially useful once an attacker reaches the walls. With a circular design like Apple's HQ, as attackers get closer to the walls fewer and fewer defensive positions can see them until you can only see them from right above.

1: https://en.wikipedia.org/wiki/Bastion_fort

In all likelihood Intel would attack from the middle of the circle...

Clearly the move is to put all AMD and Intel engineers on the inside of the circle. That way they would be visible from all locations on the ring at all times.

A 'reverse Trojan horse'? The defenders sneak the attackers in rather than the attackers trying to sneak in?

That sounds right.