A delay before trial is better for the defense than the prosecution. Crystal is a druggie, a slut, and an alcoholic. No matter how much money she gets from outside, she will spend it all on drugs and need more.
Now if in about 3 or 4 months someone were to offer her a substantial chunk of money, say $10k, to do a part in an "adult" film, she might take it. After all, her sex life isn't admisible.
Now of course it may not be admissible, but when the DVD shows up all over town, it is going to become common knowledge. It will be hard to prevent the entire jury pool from hearing about it...
Mangum certainly lives a high risk life style. So you are right the longer this goes, the greater chance that she will not be around to testify.