I don't think a garden hose is particularly less safe than any other hose. I suppose a cheap clear PVC hose might be safer since you can see the fluid moving if you're priming by mouth. But at that point, the over-riding safety issue is the risk of ingesting the gasoline.
I'd personally just a) use what you got (I wouldn't worry about the any dissolved rubber - the hose will probably harden a little), or b) if you're going to spend any money, buy a cheap fluid transfer siphon pump that has some hose with it.
Edit: I'd personally use the stale fuel in a vehicle at a very dilute rate, 5-10%?