A few quick notes, as I havent finished reading the CSs all the way through, [@R31GN], David seems more to be an SI than a full on AI- SI being a Simulated Intelligence- essentially a powerful operating computer with a voice module plastered over it to turn computation data into understandable English. 

Also keep in mind, it is generally fairly taboo to have internal organs replaced with cybernetics- though in Conrad's case he didn't really have much of a choice- just keep that in mind. Also, the idea of being more machine than man is generally looked down upon by a lot of folks (which is a bit of an oxymoron because people get cybernetic limbs all the time to improve their performance, but people are stupid/ignorant/insane, so what can you do?), so that could be a reason for why he's been passed up for promotion so many times.