I’ve never heard of this, but my guess was that he was suggesting the diesel fuel as an additive to reduce the octane and effectively enhance the detonation characteristics of the fuel. Lower octane fuels detonate more readily. Interestingly, your husband’s suggestion would have the opposite effect.
I’ll have to ponder this before agreeing or disagreeing with it. It’s new to me.
Vapor lock is highly unusual in a fuel injected vehicle. we’ve had long dissertations on the subject. Basically, the entire fuel system is under high pressure from the pump to the injector, so the opportunity for fluid boiling just is not there.
I don’t know why your vehicle stopped. It may have been because the system was unable to compensate for the sparse air. But I find the post interesting and anxiously await the inputs of others more knowledgable than I.