I might be wrong, but I find such statement inaccurate.
Testimony offered under oath in state courts will be reviewed by federal courts.
After fifteen years (15), some of the original witnesses might not be alive, or their recollections of the events have become obscure. The long records of Florida court must be reviewed by the federal courts and taken into consideration, even if if new testimony is taken from previous witnesses.
Otherwise, how can a federal judge rule on whether Terri Schiavo's right to due process was respected in the state courts?
"after 15 years some of the witnesses might not be alive.."
What a ridiculous statement in this case as we are dealing with avoiding the cruel death of the principal interested party. But your concern is that the testimony of some already dead person should be given priority?