I don't think that people here are fully appreciating what can happen on a bike that is not necessarily the Terminator or Machete "riding and gunning" their way through a major city. Consider other possible scenarios:
1. You stop on a backroad at a stop sign, look both ways and are about to proceed when you are struck from behind just hard enough to knock you from your bike. You regain your composure and pick yourself up, approaching the driver to exchange information, only to realize that the driver and his passenger, who exited with a gun, intend to take your bike and leave you a pedestrian.
2. Your waiting at a stop light as three friends cross the crosswalk. Just as they reach the end and are about to step onto the sidewalk, the largest grabs you and yanks you off your bike, the smallest grabs the bike, and the final one pulls a knife.
3. You've been riding for hours and you pick a convenience store at random to stop and get a drink. You pull into a parking spot and kick the stand into position. Unfortunately, the store was chosen by a flash mob about two minutes before you arrived and they are now exiting the store as you remove yourself from your bike. However, four or five of the guys in the mob think your bike would be fun to ride around the neighborhood and the rest of the mob decides to convince you with fists and clubs.
Convoluted? Sure. Unlikely? Maybe. But the point is that you should be able to draw your weapon on your motorcycle the same as if you are walking down the street. You are much more exposed on a motorcycle, especially when in traffic (multiple so if you won't or are in states that make illegal lane splitting) or at a stoplight or sign than in a closeable, lockable car, van or SUV. Having a gun in your saddle bags or where you can't draw it immediately on your body may leave you undefended when you need it most or, even worse, arm the motorcycle thief that successfully steals your bike!
Flash mobs are just one example of how criminal behavior is evolving, and even though it sounds cliche, we even have to expect the unexpected. That which sounds ridiculous today will be standard criminal practice tomorrow, and I want to keep my life and my bike.