I'm not playing missions or anything like that. I'm just selecting the Skirmish option at the prompt, adding the AIs to play against and then launching the skirmish. I thought it was odd that the Rules.ini wouldn't work in this version, given it's just a human versus AI thing.
Alternately, is there a way to make the AI as intelligent and aggressive as this one in the regular game? (say, through First Decade RA1?)