Sorry to hear about your garage, but glad nobody was hurt. It's common for alot of people to use linseed oil in attempt to be a little period correct. However today's linseed oil isn't even the same anyway. It does contain some flax, but very little. I suppose because of the name on the can it's poised as a natural product and therefore used in our historical time. Boiled linseed oil is a misnomer by the way, oil does not "boil", it's the additives to create a rapid polymerization to how it gets the name boiled. Blown linseed oil is oxidized much the same way. Linseed oil was used as a binder for paints, but hasn't been for several years now since emulsion paints opened the door into fast mfg.
There are natural linseed oil/flax oil, from the seeds you can find it in health food stores of course. It's pretty expensive. Raw linseed oil is still available, but is still flammable so were defeating some purpose by using it still.
The boiled linseed oil most people are using today contains alot of oxides-- manganese, cobalt, naptha, benzene, this is where it gets it dark color. As mentioned before were talking cancer causing. You don't have to eat it, just breath it or absorb it through your skin by handling it enough. Again it's flammable, but who's going to be using flames near the tent? It's probably an uncommon safety thought for someone who doesn't use the tent often, but all it takes is the right spark one time.
Bottom line is, rain is PC! Smoke your fur and hide.