Well
I woud hope that any glider pilot/ PPL would realise that an approach to any airfield with potential instrument approaches in Class G is to be treated with the utmost respect.
Situational awareness hasn't ben mentioned but is key here. If both pilots were taliking or even monitoring CVT then they should have been in a see and avoid or (the Rand pilot) does not cross the approach.
I have to admit there are many private pilots who do not fully understand this or get into overload so readily that they can't practise it.