Apparently it is quiet, I just stumbled into here. However I do have an opinion based on mechanical and fabrication training and experience. The Germanicon's used pretty much everything they captured, to include who knows how many Bren Gun Carriers.

However there is a vast mechanical difference between a small vehicle such as the Goliath (small, not too much material involved) and a Bren Carrier. Manual controls require some sort of servo (hydraulic or electric) and that requires significant engineering and material effort to make even a wire controlled vehicle serviceable enough to crawl over a few hundred yards of ground. So, no, the idea may have been entertained, but rejected due to the impossibility of receiving such resources for any number of vehicles in my opinion.