Replace ignition switch?

I would appreciate a fast answer if anyone has one. My car left me stranded out of town on Memorial weekend and I'm at the mercy of the local Buick dealership.

The car drove fine all weekend. I even drove 800 miles to Iowa and back last week, no probs. No electrical issues, lights dimming, etc. However, I woke up Monday morning and the car wouldn't start. It had power - windows, lights, etc. all worked but it wouldn't start. Not even a turn over or click, nothing.

We ruled out the battery and such and had it towed away. The towing guy mentioned that it is probably the security system shutting the car down.

Today the buick dealership called and said that the ignition switch was shorted out and that was locking the security system. $265 to replace the switch (ugh).

I can't take it anywhere else but does this seem realistic that it's the ignition switch that would shut down the security system so that the car wouldn't start?

Thanks!
Julie