Yes, I can see where a heavy concentration of low C number (Methane, Propane. LNG, or gasoline) vapors would cause trouble in diesel engines (to include catastrophic failure and uncontrolled governing) it is unfortunate that the sources quoted did not specify what that concentration might be at the time of failure.
We do not work in refineries (or drive our campers there) where the risk of massive releases of gasoline could occur, but
we do frequent gas stations where a large gasoline spill would cause this issue, provided, as quoted in the articles, the diesel was running at the time of the spill. I suspect a destroyed engine would be the least of our problems at that point.
For propane to cause this problem, the density of propane would have to be quite large to generate the density required to continue to run a diesel engine after you turned the key off. The smell alone would have alerted you to a problem long before a combustible concentration could have built up.
I have a Bachelor of Science in Chemistry from Villanova University; was a flight and ground safety officer for two Air Force Wings; trained at the University of Southern California in aircraft accident investigation; and investigated major aircraft accidents including loss of life and frame in the USA and overseas.
While my expertise is NOT (repeat NOT) in refinery safety, I am fully aware of aviation fuel safety and received training in major accident response at the Air Force On-Scene Commander school.
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW