Well much about the Inquisition can be found here:
A really short summery is that in order to join it there only has to be the utmost faith in the Emperor. In order to become an Inquisitor there also have to be latent Psyker powers present in the candidate. Something Wroth has.
- What I however guess is that Wroth in fact is human but because of battle, age and augmentation looks like an cybernetic-zombie as a result. This extreme is not uncommon however, the devotees of Mars (Adeptus Mechanicus) often are not something someone would call human despite being human-enough in order to work for the Imperium.
Another long story short is that the Imperium has only one strickt rule about this kinds of augmentations and that is that the brain is kept human. There are some Warhammer (pre-pre-heresy) stories about AI gone very much wrong in their universen (think about the Terminator movies).
Another interesting side-character would be:
Glavius Wroth is a staunch Amalathian, an outspoken champion of order and unity in the face of the manifold threats that the Imperium faces. Unaligned to a specific Ordo, Wroth is a powerful and experienced operator within the Ordos Calixis, well-connected to the pillars of Imperial order across the sector. However, he has arguably as many enemies as he has allies within the Holy Ordos and must maintain a careful balance in order to survive – chiefly through knowing far too many secrets to easily move against. Wroth is a tough and robust figure with a subtle mind and a blunt tongue. His bearing and manner give the impression of a no-nonsense Arbites Investigator, and this bluff exterior conceals much of his true depth and intellect. Little is known of Wroth's distant past or apprenticeship within the Inquisition, a state that he undoubtedly deliberately maintains, but his present reputation rests in no small part on the excoriation and execution for heresy of his fellow Inquisitor Eustis Ionfell and his network.
Note: Amalathian is not a race but rather a philosophy within the Inquisiton and Caius obviously isnt the same name as Glavius. Despite this he might have been the inspiration and as such is designed as a Neutral Inquisitor.