Looking at the component values again, all three interpretations in my first post look like slightly mutated versions of CGS24, discussed here:
(the wire going upwards is 100k to +15V)
Except that it’s used for trigger to gate here, not gate to trigger 
(But all these circuits are crazy imprecise, since they depend on the trigger voltage, which isn’t exactly standardized. See here for a bit more on that.)