I worked at a golf course in summer through college. In the second year, they put me on the spray crew and I liked the responsibility. The super gave me a chem list and I mixed it and went out spraying. One day, he came running out right after I pulled up to the first green and told me to dump the tank. In that one instance, I had put a similarly named product in by mistake.
It turns out that every day, he let me do the work, but also verified as I left by checking the dumpster or levels left in the bottles he had ordered mixed. He made me feel good by trusting that I would do a good job, but also verified my work, as a good manager should.
In that light, I think the super there had several chances to catch the mistake - upon ordering, upon recieving the materials, upon loading it into the spreader, etc. Given its a half million dollar mistake, there should have been some checking in order.
JK, given how hard you have been on supers here in the past, your compassion in this case is stunning!