The Porsche Carrera GT was one of the very last Porsche models that lacks the modern vehicle stability and traction controls designed to keep drivers from dangerous oversteer or understeer. Indeed, if you drive the current-model Porsche 911 GT3 or 911 Turbo, it’s very hard to get into a dangerous handling situation due to modern stability and tracition controls on the drivetrain.
It's clear that the car hit the tree at a high rate of speed. A stuck throttle can be overcome by bearing down on the clutch but this car has so much power the driver might not have reacted quick enough to avoid a spin-out, thus striking a pole and tree.