The reconstruction of the slide area is going to require a couple of hundred tons of fill material. Our flatcars can haul 10 or 12 tons per trip. Do the math. Then we have to unload and place the material in the right place. Sure, we could do it with picks and shovels and wheelbarrows, but that doesn't make sense. And the work necessary to lay "temporary track" 1000 or 1200 feet is just as difficult and intensive as building permanent track. As Mike has noted, if heavy equipment is moved in to rebuild the embankment, it must get back out the same way.
In addition, where does the manpower to do all this work of building temporary track and repairing the big slide come from? As has been noted elsewhere on this forum, except during the spring and fall Track Meets, especially in high summer, rounding up enough folks to man the station and run the trains is sometimes problematic.
The contractor who removes the big stumps and helps lay new culvert pipes leaves the subgrade smooth enough to drive on, so why not take advantage of heavy equipment for this project? Sure, we might be able to complete this exercise ourselves, but how much time and energy would be spent here that could be more profitably engaged elsewhere? Remember, we're talking about weekends here, and quite a few of them, one right after the other, to do this kind of a job.