Unless the "motors" are marine rated with spark screens gas or diesel doesn't matter except for the fuel type. This be alternators, blower motors, etc.
Looks like they need an arctic emissions package for the diesels, otherwise, yes gasoline trucks are the better choice for that kind of use. Weather doesn't matter as much as the no-load, low power, low speed use. Even then you get to the spark plug fouling never warm the engine up problems. The Ice Truckers TV show touches on the emissions issues as well.
It would be interesting to know if they are buying USA emissions trucks when this level of emissions are not required for the area the trucks operate in?
Last company my dad worked for had 600 1/2 ton GM pickups with the 4.3 V6 gasser over in California oil fields. Most went over 200K with zero engine issues and 5K oil changes. The GM fuel pumps and level sensors didn't last while muddy weather broke axles in the fields from getting stuck. (Couple pickups even broke the frame although I think they were Fords.) The 1/2 ton V6 was the choice for fuel economy. Heavily loaded trucks were 3/4 tons. So I doubt the gasoline engine concern in oil fields. Welding is common in oil fields, eh? So I vote it's a fuel supply issue or blind incorrect for use diesel truck choice.
Halliburton loved their 1 ton diesel Fords.