Offshoreonly.com - Tether kill switch wiring

I am rewiring alot of my boat, and adding a factory tester switch to my throttle. I went with the factory one so its a nice clean look. I have the mercruiser 4000 controller. I bought the switch part number 87-19674A 07. It fits and installed very easily. I went to wire it up and it's not how I would expect it to be. The switch is a normally open switch. It closes it's contacts in the off position. From what I have found, this way is for an outboard. It shorts the ignition signal to ground shutting the boat down. What I was expecting was a normally closed switch and just switching the purple wire to my coil. I don't want to short my 12v igniting wire through the switch. Unless this is normal then I will. My question is does anyone know the correct part number to get that same switch in a normally closed position? Or is shorting the 12v the common practice?

I realize I can make this switch work with adding a relay and rewiring. I will do that if need be, but I would have less parts to fail. Also be more like the way it was from the factory for later troubleshooting. Thanks in advance.