This makes sense to me and might just need some context. My grandfather died from mesothelioma - a dust based disease caused, in his case, by asbestos. As a 20/30 year old plumber, he was using asbestos products without any protection as it was assumed to be safe. Later in life, he developed mesothelioma which effectively causes your lungs to fail.
These diseases develop over time so there are claims that are unknown at this point in time but will appear in the future. It makes sense for a fund to be set up to cover future claims.
What makes you think it isn't? The courts don't randomly choose numbers. Actuaries are involved to calculate the future cost of these events in order to determine what funding is required today.
FTA - "The proposed settlement would be paid out over 25 years"
Inflation alone will wipe a big chunk of that value. Evan at 3% inflation, they will save over 2.5 billion in real dollar terms.