You are assuming the supply of diesel goes to 0. Instead there is a reduction, not elimination and as a result, demand destruction will happen in the US just as its been happening for months outside the US. (This is partially what allowed us to avoid a crisis in March)

Trucks will stop delivering trash (ex. China dollar store crap, lower margin non food items and a billion other nonessential items). Food prices go up, people will do without less desserts or fancy foods but enough deliveries continue with the fuel saved that no one starves.

Now imagine if we replaced only 10% of diesel trucks with electric. Hell just focus on the short haul trucks. That unburned diesel could have helped buffer the remaining fleet.