First off, I don't doubt your auto mechanical skills over mine anyday, reading about some of the mods you did to your vehicles. I also give you congrats, for giving the OP'er an actual, driect answer to his original question, how to disable the chime device.

Now for the other part of your post, on the chime device being a 'real time device" acting immediately. I'm sure you'll agree, the chime could sound off for all sorts of problems with the vehicle as you drive down the road right? So lets say you are driving down the road and the chime sounds off due to "something (a rock?) blowing a hole in your oil pan(as per your scenario) and you start" losing oil pressure due to loss of oil of course, does the chime tell you what is wrong with the vehicle or just alert you to some type of problem or issue happening now? What do you do next, you start looking at the dash for a flashing icon warning for a specific problem(low oil pressure), check your various gauges(for low oil pressure) or you look at your message center (if you have one) for a specific warning message(low oil pressure) right? It seems to me, the other 3 backup warning signs/devices give you a specifc problem listed, where as the chime just tells you, "hey somethings up with the vehicle", you better start looking at your dash icons, gauges and messages.
As for the chime being an immediate sounding device of a problem isn't going to save your engine from the hole in the oil pan, because you won't know what the problem is until you look at your oil gauge, low oil pressure dash icon flashing or the low oil pressure message on the message center and by then, it will be too late anyhow to save the motor. You would still have to wait for one of those other non-immediate warning devices to go off before you would ever know what is wrong with the vehicle. Am I wrong with this assumption or did I miss something? This is the problem I have with your oil pan scenario and the relation to the chime device.
For me, the chime is useless and a nuisance since it goes off for all sorts of reasons or issues, some non serious and I will see a lighted up dash icon come on or spot a gauge spiking or see the message come up on my message screen as soon as it happens if there is a serious issue with the engine or electrical system, because I pay attention to what I am doing behind the wheel of a car and the internal functions associated with the care of the car. I could also mention that when the excessively loud warning chime sounds off, startling you as you drive down the road in traffic, it can cause you to take your eyes off of the road all of a sudden to check for the issue, not at the best of times in traffic, because you fear a serious problem with the vehicle. That in itself is a danger to you and the other people driving down the road around you and could cause you to have an accident.
BTW, some of us drove cars/trucks for decades with nothing more than quiet dash gauges or flashing idiot lights(dash warning lights) before they ever came out with these loud, nuisance warning chimes we are speaking of here and got by without them just fine and no major problems. Other than this I was glad to see you give the OP'er a "helpful"

direct answer to his question.
Merry Christmas and Happy Holidays to all!