Those side struts that have the tie downs on them look like they could bend or collapse if the road were a little rough and the bike started pulling side to side. Plus, if you hit any bump the rear end of the bike would go flying pretty high.
I would think you would be very likely to end up with a nasty rock dent from road crap being thrown up at the bike. Not only that I thought that when you tow a car that way it can count up the miles on the odometer. Would that do the same on the bike?