And 18,000 cows? Sounds deliberate to me. That is a staggering number, too many dead animals for a mere "accident".
As long as the insurance company pays off, every one will be happy no matter the actual cause.
This explosion killed cows over a very large area, one larger than several football fields. If such could have happened where are the reports of the same thing happening and killing people or cows or in fewer numbers and on a smaller scale? I searched for those types of incidents at the time this happened and could find nothing similar. Of course, with the advent of AI, if I searched now I might find news articles of several similar cases.