the transmission is a "meshed" transmission. if the engines isn't running the transmission isn't being lubed.
i say don't do it.
+1 And then some. Wouldn't hurt the rear end since it runs in its own oil bath anyway, but the tranny is another story. Besides, I've seen where a bike being towed like that had almost dropped into gear when it hit a nasty bump. Did a pretty good job on the innards as I recall.