I agree with jhenry.
The problem with your reasoning, Mr. Pond, is twofold for me- first of all, I am one of those who prefers to ride a "naked" style bike- no bags or storage other than a duffel held by bungees to the rear seat on most occasions.
Second, I don't want to be moving the gun back and forth from my body to the storage if and when I get on/off the bike.
And I suppose third- if something really did start to go down and you were a few steps away from your bike, would you have time to get to your bike, open your tank-bag, get your gun, and deal with the issue? Seems like a lot of time to do that, to me.
I have heard the get-off injury argument many times. I figure if it happens, it happens.