Tamiflu and related anti-virals are not vaccines. Two totally different things.

It's only "worthless" if the next pandemic is a Tamiflu-resistant flu, but like I mentioned earlier, no one knows what disease will be the next pandemic. When the decision was made to stockpile it, the avian flu that experts were afraid might become the next full blown pandemic wasn't Tamiflu-resistant like this most recent case. Tamiflu is not a silver bullet to cure any flu epidemic. It spares some infected people from death, and for the rest of the populace, it simply buys you time until either the pandemic runs its course naturally or a vaccine is developed. Vaccines take many months to produce in quantity, even in the best case scenario.

And people would be screaming bloody murder at the government if the next pandemic is a flu strain that Tamiflu works against but no Tamiflu was stockpiled.