Helium for party balloons is low grade and not pure enough for chip fab use, so stacking up birthday tanks won't keep TSMC running. Industrial grade helium has a restricted and oddly international supply chain thanks to regulation and a few weirdly-placed depots. The US 'helium stockpile' isn't really a menu you can just order from when a factory across the planet runs dry, especially if offtakes and logistics are tied up by decade-old government contracts. If you want to see supply chain fragility, try pricing MRI-grade helium after a shutdown and watch everyone in medical procurement panic quitely.

after what kind of shutdown?