Mitch, so sorry to hear about it. I can understand your disappointment, because I've been there, done that - maintaining my NSX above and beyond what's recommended, taking care of every little thing, only to have it all go south in an instant.
As to why it happened, when they take the engine apart, they may be able to tell what sequence of events led to the catastrophic failure. As you know, in my case it was caused by the separation of the harmonic balancer pulley, which then rubbed into and through the timing belt cover and jumped the timing. This may or may not be what happened with yours.
In my case, the top and bottom of the engine were both shot, so both would have needed rebuilding. I was looking at an estimate of $13K for a rebuild. I looked at the listings on NSXprime as well as calling the big servicers of NSXs around the country, and within a couple of days I had located 4-5 used engines. This was five years ago and 3.0-liter engines were generally running $4-6K and 3.2-liter $8-10K. I wound up buying a used 3.0-liter engine with the same mileage as my original one, and the whole bill, including the engine, cross-country shipping, labor, etc, was under $10K, less I got another $1K back for my original engine. As it turns out I'm glad I saved thousands by going the used engine route. They were also able to turn it around pretty quickly, no waits for parts, etc.
Oh, and while I was at it, I had them replace all the parts with new ones that you would want to do anyway for routine maintenance - the timing belt, water pump, and all the cooling system hoses. That way you won't have another big bill for scheduled maintenance for years, because you can reset all the service intervals. So in a way that represented savings, too (unless you just had all that stuff replaced, in which case the savings are minimal).
Timing belts do indeed cause catastrophic failures, and if you talk to any of our experts who service a lot of NSXs, they can tell you about ones they've seen. However, when it is caused by a failure of the timing belt itself, rather than something else which causes the timing to jump (as in my case), that happens only when the timing belt isn't changed at the recommended time/mileage interval. That's clearly not the case with Mitch's car, since he had all the maintenance done ahead of time. Anyone who understands this and read Mitch's posts would not have jumped to the erroneous conclusion that the failure of the timing belt itself was the direct cause.
