That just looks sketchy. Bit of rough pavement, car hits a pothole, I can just see the rear tire of the bike getting air and bouncing all over the road. One of the straps comes loose and the front end slips a bit, over goes the bike getting dragged down the road on it's side.
I know my 4x4 truck says to put the transfer box in N when towing to prevent transmission damage....the t-case pumps lube from the driveshaft's motion, whereas the transmission needs the engine running.
"We have not received any reports from our consumers with regards to any problems associated with the Slick Wheelie and shaft-driven motorcycles. But know that some shaft-driven motorcycles use a lubrication pump that requires that the motor be running in order for it to work properly. Should you have any doubt or concern about your specific model, please contact your motorcycle manufacturer, authorized mechanic or dealer."
So in other words, nobody's complained yet, therefore not a problem.