Completely - you could also say that reducing DNA damage might actually also decrease immune system surveillance that might be happening causing worse than expected outcomes. Imagine if a lot of cells that might have killed themselves stay alive because of drinking coffee might actually turn out to be a bad thing. We just don't know enough to say for sure and these sort of studies are wildly difficult to get mortality figures from.

We still aren't even sure what general diet is fully optimal long term let alone if one constituent can give actual life expectancy benefits.