Re: ...helium currently comes from natural gas..."
" As for the fire thing - it was the fabric of the Hindenberg that burned, the hydrogen was incidental at best"
It was covered in canvas, with several doping agents. However none of these are highly flammable (please don't start quoting rubbish about powdered aluminium and iron oxide).
You may as well say pouring petrol on a cotton t-shirt on and lobbing a match on it, the resulting fire was caused by the t-shirt.