I don't think they actually believe a Rocket to be ugly.
But if I would ride a M109R, this would be the only thing I could bring up in a comparison, to still feel comfortable with my own bike...
If I was a M109R rider, I would not be in a position to call a Rocket slow or outdated or too heavy, or even pick on the handling. I couldn't grumble about it's brakes as well, couldn't curse about cardans and overly fat rear tires in general, and it wouldn't be an option to look down on the brand name.
In fact, there is absolutely nothing I could use as a reason to feel superior, because the Rocket is obviously superior in just about everything. What an uncomfortable situation!
So what would an unsettled M109 rider do, to feel better? Probably put the look of the Rocket down, as a last resort...
Or ... just buy one and enjoy!