If it fails, it would be fixed soon. The driver still has the window. I'm struggling to see how an immediate failure of speed readout etc would immediately endanger the car? Assuming it performs no control function.
Door ajar? Seatbelt loose? Now we're just getting into paranoia scenarios. What if a nuclear bomb landed and there won't be enough gas to drive me away from the blast zone!
The one vehicle I have right now with ABS has intermittent ABS issues but a soft failure mode. Newer cars rely a lot more on ABS (especially in off-road modes), same goes double for motorcycles. Losing ABS/TC on a motorcycle drastically changes the envelope of safe brake application. If your muscle memory for safe brake application is (mis)trained to rely on ABS/TC at the limits of available traction, losing ABS/TC will very easily lead to a front wheel lockup or unexpectedly losing the front/rear in a lean.
It's true that you probably won't die immediately. But for most people, driving a long distance without a cluster display would be extremely dangerous. Especially at night on an empty road. For me, I start relying on the readouts for speed and rpm around the four hour mark. Tired brains don't work well.
Which means you probably have to get it fixed ASAP. If that happened more than a couple of times with a car, I'd sell the car / not buy it in the fist place.
They stopped making this car in 1983; it is far beyond it's design lifetime already, and was never a particularly reliable car to begin with, from my understanding. Like most classic cars, you probably shouldn't drive it unless you enjoy maintaining it, and are okay with (and carry substantial liability insurance for) a car that is dramatically less reliable and less safe than a modern car. Like most classic cars, you probably shouldn't drive it places where you are likely to die or otherwise suffer dramatically bad consequences if it breaks down. This isn't a criticism of the Delorian specifically as much as it is a truth about early '80s automotive engineering and running vehicles beyond their service life.
Of course, as a society, we've decided that this (tradeof off cool car vs danger) is a reasonable choice to make; we don't force people to buy newer cars because they are safer. Within this context, the addition of a special instrument panel seems to me like it's not adding substantial additional danger to the system.
Also it did really well in the crash tests of the 80's and current owners baby them, so the insurance is pretty cheap.
Wow. I never rely on readouts. Always use the window :)