I think folks outside of Colorado probably don't have a real appreciation for the wildfire danger (save of course fo our members in California and Arizona!). Remember that in 2012 and 2013, residential sections of my own town of Colorado Springs itself were wiped out in wildfires. The D&SNG was suspected to have started the massive 416 Fire near Hermosa in 2018 and litigation is ongoing.
Diesels really are the only way ahead if the D&SNG is to survive. Again, they're not looking to do away with steam (otherwise they wouldn't have embarked on the massive conversion program to oil burning for the former D&RGW K-28, 36, and 37 fleet) but they need options on high fire threat days.