Well thats a new one on me, when I worked in the RMAS, we did indirect tows when stern tug to assist in turning the the towed vessel when it was moving forward. We all thought at the time that this is a good practice, but we found out afterwards that it had been calculated that in theory you can roll a tractor tug when carrying this practice.
As I said at the start it is a new one on me these carousel tugs, I cannot comment on them as I have no experience of them, but all the same I would still be cautious about girting one when the tow was moving through the water.