Well, I myself don't have that much of an opinion on weather or not Kurt killed himself or was murdered. Their are a few things to consider though: At the time of his death he had enough heroin in him that he probably would have died from it... also meaning he would have had one rough time pulling the trigger. Second, these rumors started popping up when (somebody will remember this guy's name... but I can't) claimed that Courtney offered to pay him to kill Kurt... soon after he was hit by a train. Now what all of that means, I can't say.
What I can say is that I agree with Les Claypool: Courtney has used Kurts fame and death to her advantage as much as possible.

From: Coat Tails of a Dead Man, Primus
He wasn't lookin' for fanfare or fame but it all came around just the same. He then met a girl with desire in her eye, he gave her love, she took his name.

The times they were good, the times they were bad, most times it was just in between. The hard pill he swallowed was the times that they had, she put on display for all to be seen.

Some find their solace in work or the lord, she was quite content in her dream. When his eyes they burned from the bright lime light, he found comfort in the bottle of Ol' Jimmy Beam.

One day from the depths of his deep darkened hole, he reached out for something to feel. She offered back nothin' but lack of respect so he left himself out with two barrels of steel.

She cried in the day, she cried in the night. She cried loudest when someone was near. Whether crying for him or she cried for herself, the bigger the camera, the bigger the tear.

Most folks agree that she was living a hell and publicly she showed her pain. And never once was there a thought for herself, and the ever-growing slices of fortune and fame.

Now on the coattails of a dead man she'll ride
On the coattails of a dead man she'll ride.
On the coattails of a dead man she'll ride, she'll ride
On the coattails of a dead man she'll ride, she'll ride high.