The inherant design of the SiG Classic "P" Series, of which the P230 is one, mitigates this factor very well. There are no guarentees, however, but let me explain what I mean.
The hammer at rest does NOT make contact with the exposed end of the firing pin. To get a Classic "P" Series to fire you HAVE to cycle the trigger. Might sound basic and almost stupid but it is why I love SiG's so much over the 1911/BHP style cocked and locked systems. What that does is accuates a cam that lifts a firing pin block located in the breech block assembly just prior to releasing the hammer seer to travel forward allowing it to strike the firing pin. There is also a hammer block mechanism that allows for the decockig lever (should it ever fail during use) to not disengage it so the hammer can be placed in its rest position safely.
If you are really worried about it, don't drop it on the hammer. Seriously, I wouldn't be overly concerned with an AD with a SiG from being dropped.