That's probably why the fuse was missing. There's very little space between the contacts under the button. So, if there are any metal particles or the mechanism is broken it may complete the circuit. I'd check both buttons first.
Disabling the airbag is tricky; typically most just disconnect the battery, however many have triggered the airbag light by doing so. Ask me how I know. And it cost $50+ to have it reset at the dealer.