We don't know if he came down on his reserve.
It may have popped open as he hit the tree or come out of his harness as he fell through the branches.
If it was fully open, why didn't it snag above him, instead of the paraglider canopy?
It looks to me like the paraglider was above him when he hit the tree.
To my mind, there is no way the parachute would have ended up where it is if he had come down on it.
It didn't snag on anything.
Why are so many paraglider pilots "error prone"?
Because they are not really pilots.
They're riding big, fat floaters with minimum control that often vanishes in turbulence.
Real pilots master pitch, yaw and roll.
Real pilots do not substitute lift for pitch.
Real pilots dive to trade altitude for the kinetic energy to maneuver.
People on paragliders are going along for the ride with severely limited pitch control.
They are parachutists on critically balanced and dangerously modified parachutes that threaten to collapse if they go fast.
I call them operators so as not to offend real pilots.
They operate the paraglider until their lines go slack, anyway...
Then they throw another parachute.
It's not really a decent example of airmanship.
In fact, its embarrassing.