Why didn't the D&RGW scrap the remaining cars on the Silverton Branch?

Dick Bell's photos of the outfit cars taken in Silverton in the 70's got me to thinking, and I apologize if this has been answered before, but, does anyone know why the Rio Grande didn't finish the job so to speak and scrap the majority of the NG cars leftover after abandonment?

I understand that some of the DB gons were still used for maintenance work, and some of the boxcars served other functions, but, from what I can gather, most of the cars that were transferred to the D&S were not needed. Was it just a matter of difficulty with ensuring that the scrapper didn't touch anything useful, were they just forgotten about by corporate, or were there other uses planned for the cars?

Obviously, I'm glad that so many cars were not scrapped, but, if anyone knows or suspects the reason why, I'd love to hear it.

Another question...other than cars scrapped in 1970/1971, were any D&RGW NG cars disposed of after that date by the Rio Grande?

Thanks,
Grant