NSEU- you're an avionics engineer? You are arguing a bit out of your sphere of knowledge!
<<If it fails on push, presumably friction of the motor will provide braking?>>
If it fails, wouldn't that be the last thing you would want it to do??? You want the nosewheel to revert to.. a plain and simple nosewheel (at least when the aircraft is moving forward).
I can't imagine this system would ever be used for pushbacks. The pilot would have no idea what is going on behind/under him/her.
If such a device failed on push, the first thing you would want it to do is gently provide automatic braking. What you must not do is brake the main wheels- that could tip the aeroplane back. We rely on such safety braking systems every time we get in an elevator!
Why would it not be used for pushbacks (if it can hack it)? We used to do powerbacks- starting engines on stand, idle reverse and let it go- steering to ground controllers visual instructions. It works OK, but training required, and the engines tend to ingest debris. The pilot has to follow exact visual instructions from the marshaller. I sat at Dallas and watched AA MD82s doing powerback after powerback most skillfully.
If this company wants to prove itself- good luck to them, let them try. They may just do it. But all the ideas are established procedure at some time or other. It's a complete red herring harping on about failed starts at holding points- everyday aeroplanes have trouble at various places. Just today I took off behind a 757 that abandoned take-off at Stockholm. It happens...people deal with it.