In the 40K universe artificial intelligence, also called abominable intelligence, is most definitely banned on account of them inevitably trying to destroy their creators - although the Tau seem to have got away with it so far.
However, it's a big galaxy out there and the odd 'Man of Iron' escaped the purge back in the Dark Age of Technology.
One of them is wandering around the Blackstone Fortress, attempting to commune with the base itself, or more accurately its AI.
The MoI is cunningly disguised as a semi-autonomous Imperial Robot under remote control - very non AI - so is equipped with Imperial weapons such as a power fist and a gatling cannon.