I'm no microbiologist but I wonder if improper refrigeration could be a factor (or *the* factor) in this particular matter.
No. On other food poisoning causes, that would be a primary factor, but in this case, improper sterilization of the food at the time of manufacture is the cause.
Clostridium botulinum grows in an environment without oxygen—so a sealed can is perfect for it. It forms heat-resistant spores which cannot be killed by boiling, so canned food must be heated above the boiling point (to 121 C for a sufficient period of time for the entire contents of the can to reach that temperature).
This problem did not originate at the gas station. The cheese was already poisonous before it was delivered to the gas station.
I would not be surprised if that entire lot of cheese is recalled. Since food manufacturers have gone out of business over incidents like this, the cheese manufacturer may not be around much longer.
One last detail: often, botulinum neurotoxin cannot be smelled, seen, or tasted. So the cheese might have looked perfectly okay to the person who set it out for sale. In any case, it is never safe to eat food from a bulging can, or canned food that looks or smells odd.
I doubt refrigeration had anything to do with it. The cheese comes out of a can.