A strategic petroleum reserve makes a lot of sense, petroleum is part of the food supply chain and it'd be stupid to be in a position where a short disruption could cause people to starve. Not to mention the military implications if an army can't zoom around because the petrol stations run dry for whatever reason.
I don't see anything on the list of uses for helium that looks particularly time- and helium- sensitive in the way that a strategic stockpile would help with.