I have 3 containers for gasoline stored alongside my house. Two hold about 20 gallons each and one holds 10 gallons. None of them are actually airtight and are seldom full anyway. I call these containers "cars"

I think Rudeboy has it right about the potential dangers. Think about how cans of nitro get delivered. They're packed together in a box, get thrown onto a truck, bounced around on the roads, taken off the truck and thrown on the ground. When was the last time you heard of a can of nitro exploding? Common sense safety is more than adequate for the chemicals we use.

As for the "alcohol foam" to extinguish a nitro fire, I suspect what they meant was to use the same type of foam extinguisher as is used for an alcohol fire.