It's extremely incorrect. 98% accuracy on when "you'll" die would imply an R^2 of 0.98 for individual-level lifespan predictions. We are nowhere close to that.
It could mean a lot of things. It could mean "We think you'll die at 87+-5 years" and counting it as a success if you die anywhere in that age range for instance which I could believe they can predict the vast majority of the time. I doubt they are referring to the R Squared.