Real-life discrete monoflop
I'll cut to the chase and suggest a modification to your main diagram: -



Use a diode as shown so that activating Q1 is done fairly quickly when an "overload" occurs. To make this work effectively Q1 should be a P channel FET - this will allow C1 to charge to nearly the incoming power rail - in fact add a zener diode across R2 to limit this charge to 10V (in case the gate gets damaged by over-voltage).

R2 can be chosen to be a high value that slowly discharges C1 when "OK" returns high.