It was all meaningless. It was just a line put in by the script writers because they had to come up with an answers and response to the teaser trailer at the end of KH1. In fact I remember reading an article that said after they were done writing the script they had to go back and add in all sorts of stuff from the teaser(like the flashing and flying words). As much as people like to think the whole KH series was planned out meticulously it really wasn't, of course Nomura had ideas and opinions on how he would like to continue the series, it's only natural that ideas change, deviate and grow. That's why there are still differences, though maybe small, between the teaser and KH2.
But basically the line of "His eyes couldn't lie" was basically mickey's way of saying that Riku couldn't stand seeing what he'd become and the things he done.