I doubt whether that would have been the reason for the truck remaining connected after the aircraft was on the road. I think the more likely explanation for it remaining connected once the aircraft was on the road was to mitigate the ongoing risk of the shear pin in the nosegear towbar connector breaking. If that shear pin breaks and the aircraft brakes don't work the aircraft will continue rolling wherever the surface slope and gravity take it. It didn't take much to shear that pin. (Most of us groundies usually had a few spares in our ear muffs. Don't tell anyone, but I've heard from a mate that he was told some people used to slide a standard Dassault screw driver in to replace the shear pin...)
The third photograph shows the aircraft in a spot of bother, where the level of the road is obviously much higher than the level of the tow point on the nose gear, such that the towmotor couldn't be directly connected. Would be interesting to find out how they got the aircraft over that 'lip'.