I've noticed that the 1d5 critical results inflicted by Righteous Fury aren't affected by any talents, whether they boost or reduce the result. While I can understand people not wanting to a single lucky Righteous Fury result completely destroying a target it does seem strange to have talents that are all about modifying how much critical damage is dealt that don't consistently come into play whenever critical damage comes up. In the case of Crack Shot the maximum result you could get if it did factor into Righteous Fury is a 7 which would only lead to an automatic kill if it were a headshot with an explosive weapon.
Both Crack Shot and True Grit have substantial requirements, being Tier 2 and Tier 3 talents respectively and requiring solid scores in their related attributes, yet they only come into play when whoever is being hit is near death. If they factored into Righteous Fury it would make them much more attractive talents and give them a more substantial effect on gameplay.