Putting the kickstand down on my Enfield will not stop the engine, so that doesn't always work.
The problem I would have with using the kill switch, or the kickstand, on any other similar system, is that I would walk away from the bike with the ignition still turned on. This seems to be a concern with Triumph also, at least that is what I read between the lines in the manual. Despite the fact that the MSF course teaches one to use the kill switch, I never have.