5Z and Tango Whiskey and Hightime speak the truth.

Every Glider Pilot both Flatlanders and Mountains pilots should know this life saving, pretty basic maneuver.
If your in a loosing battle with roll control it IS " Time to push and apply full or Hammer the rudder.
The push to near or at zero G is so important. No stall= No spin

Just last Saturday flying out of Nephi Ut in the flats of the valley over Yuba Res I had a thermal kick me into a 80 degree bank.
Full roll control wasn't enough so I pushed to about .1 G and full ruddered it back level. I've done this about 100 times in my soaring career.

Use all the controls to the max when things start to get sideways. And always Push forward.
A early flight instructor once said to me " move the controls to make the plane do what you want it to do".
This accident that started this thread is tough to take. Poor guy hit the hill.
I think its obvious when that happens he was too close.
Awful hard on his friends and family but it sounds like it was over very quickly.
Fly safe in 2020
Nick
T