Armed or not, you made the right choice, given the background you've laid out here. The enemy in this case made an assumption that strength in numbers would prevail regardless. Had they escalated the situation, you would have been in a bad place - darned if you do (stop and confront) darned if you don't (duty to retreat).
I have been blessed in the fact that I've never been forced to the point of deadly force out of uniform, as you said, you can not say "I'm sorry". Tactically, in a one to many situation, you are still at a disadvantage (you armed, then not) - marksmanship would have to be will get you so far, but how many would have to go down before you bent the will of the mob?
How does this tie to riding and carrying? Run the scenario - could you have stopped, dismounted, drawn, fired, and maneuvered to escape attack or return fire? Ride on was the right decision, armed or not, because you are here today. Change any single detail or action of the scenario, and the entire outcome changes. You had to consider the best course of action for you entire group, which you did, IMHO.
Think about this next time you are at the range - how fast can you draw (if the range allows) raise from the ready position, acquire the (static) target, and fire one well aimed round? Now two on one target, now multiple targets? Now move to cover while engaging the target. How quickly can you stop the bike, draw, acquire, fire?
Training can never stop. No one can give you the right answer for any give situation during the event- you can only come to the best answer you can at that exact moment time.
practice. practice. practice...
Dad finally was ready to do battle, I did not want to end my motorcycle vacation in an Arkansas jail. Finally, they all got around us. To this day I feel a tinge of cowardice. To let that go was very very difficult for me. The thing is, they had no idea what they were up against. They could not have known that the "sheep" in our little group were in fact "sheep dogs" that were armed. A confrontation would have ended very badly for us all. Dad taught me at a very early age that carrying a weapon created a certain responsibility. A very heavy responsibility. Once you pull that trigger, you can't say "Sorry" and take it back.