The engine start problem at the holding point is a complete red herring (ie not a factor at all). Remote holds are common now, with aeroplanes starting engines unmonitored by ground staff. Engine start failures are extremely unusual. I don't see why that was raised. Aeroplanes can go around breakdowns, and those breakdowns can easily be taxied eventually out of the way. Not a problem to this system.
I would be interested in seeing if the system can work. By all means it should be installed in a test aircraft and prove itself on different types and in different weather conditions. I'm still sceptical, but from the number of times I have been totally wrong in the past, that is certainly no disadvantage to Wheeltug! Let's see it work, and do its thing, even in the wet, without overheating or causing a hazard of its own. If it works, it will sell.