Maybe superluminal travel is only possible along specific star lanes and if one happens to venture outside them in transit it results in a feedback loop that burns out the drive and leaves the ship stranded in interstellar space?  In order to make sure you stay in the lanes you'd either need an extremely powerful computer or a somewhat precognitive individual sensitive to the void?  Maybe before the machine wars AI navigators were common but during and after the war void sensitive pre-cog navigators became commonplace?

So you can forego using biological navigators, but only by spending quite a bit more on a large and clunky unintelligent machine since AI is prohibited?

Just a suggestion [@Polybius][@GreivousKhan].