I always thought my budgerigar weighed nothing at 30grams (about an ounce), but he's not even close.

A word like "extinct" sounds like an absolute, and a rigorous statement would include a detailed disclaimer about the limitations of talking in absolute terms, such as "within the limits of our knowledge, and we could be wrong, yadda yadda."

When talking amongst scientists, those disclaimers are unnecessary because scientific thinking is taken for granted. Thus we talk in abbreviated terms, for instance where "extinct" implies "extinct, with all of the usual disclaimers."

But I think scientists have to remember that this is a habit, and most normal people don't get it. And then our words get filtered through the press. I think an article like this could include a brief working definition of "declared extinct" which would help reinforce the idea that what we sacrifice as the price of scientific knowledge, is absolute knowledge.