Honestly, this is a pretty minor inconsistency. I would be concerned if he started exaggerating how much they hung out and saying that they used to call each other every day, but "He said she was a friend seven years ago and now says she was" isn't a smoking gun. We don't know how often they saw each other or how much they interacted on those occasions. There have been times where I looked back on (non-romantic) relationships where I considered the person a friend but, upon reflection, realized that it was more of an acquaintance relationship than anything. It's fairly subjective stuff.
"I hope those *****es are dead" is an awful thing to say, but it sounds more like the angry outburst of a 19-year-old who clearly wasn't a great decision-maker at the time and incorrectly thought that Suzie was the one who ratted him out.
I'm more concerned about evidence and someone's ability to pull off a crime like this. I don't think three guys who broke into a cemetery high on LSD and then got caught because they tried to pawn off the gold teeth using Dustin's ID card are competent enough as criminals to pull off an abduction and (presumed) triple homicide, get rid of all the evidence, and get away with it for nearly 30 years. Using your own ID to pawn off something as strange as teeth, only a short time after the break-in and a short distance away, is amateur hour. IMO this was the work of somebody who wasn't new to committing violence against women and knew how to cover their tracks.
