The GetAC() function is virtual, so it should call the correct one for bots. The problem I see is that the function signature is different than the base class.
Code:
Mob: inline virtual sint16 GetAC() const { return AC + itembonuses.AC + spellbonuses.AC; } // Quagmire - this is NOT the right math
Bot: inline virtual sint16 GetAC() { return AC; }
I'm actually surprised that #showstats doesn't blow up on a bot or mob. It appears the ATK is displayed using this->CastToClient()->GetTotalATK() for everything, not just clients, and that function doesn't exist in the base.