The minute anyone says that Jason had a part in his death because he went after the Joker, I have to automatically assume that you either haven't read A Death in the Family or have absorbed the information from a post.
Here are a couple of true statements that you would know if you read ADITF:
Jason didn't know the Joker was in the warehouse.
Jason didn't go into the warehouse to save his mother from the Joker, she told him to come with her so they can talk about what the Joker wants with her.
Jason was told that the Joker wasn't in the warehouse, that he had left a while ago.
Jason was given faulty information and his only sin was believing his mother.
Jason sees the Joker going into Sheila's tent and gets worried for her safety.
He says, "this is a job for BATMAN and Robin" not JUST Robin. He wanted Bruce's help.
Bruce tells Jason not to handle the Joker alone and to wait for him.
You could say that this is the page where he disobeyed Bruce, but all he does is want to talk to Sheila about the predicament she's in. Again, he doesn't look for or go after the Joker.
Sheila moves them into the warehouse so they can talk privately.
HE IS EXPLICITLY TOLD MY HIS MOTHER THAT THE JOKER HAD LEFT A LONG TIME AGO. And that turns out to be a lie.
So all of this happens without Bruce's knowledge and what does he think in minutes of coming back?
(Sorry for the blurry picture)
"I warned you not to take the Joker on by yourself." He didn't.
"I begged you to wait Jason, but of course you didn't."
"You never listen. Why. WHY?" He has multiple times.
Bruce has no idea what happened, but automatically assumes that it was Jason's fault. Even when Sheila tells him with her dying breath what happened, he still calls Jason reckless.
She tells him how much of a hero he was in his last moments, and instead of telling people that, Bruce basically tells anyone that he meets that Jason was disobedient. He has essentially erased what happened in the warehouse - the part that he knew - and replaced it with a completely different narrative that makes Jason his scapegoat.