Pentobarbitone (also called pentobabital or nembutal) can be taken orally and has been known to be a drug of abuse under the street name of "Yellow Jacket". You can get it as a yellow capsule (http://www.drugs.com/imprints.php?action=search&drugname=nembutal+sodium), which I imagine is where it got its name from. It is also available as an orange capsule. It looks like it is used for suicide and an organization called Exit International helps people get it (http://abcnews.go.com/Health/MindMoodNews/story?id=5481482&page=1). So he did not have to inject it. The first toxicology report stated that no drug was found in the stomach contents. I would have expected some to be there if the pink liquid was from the pentobarbitone. I am surprised nothing was found in the stomach. Its hard to say what the pink liquid was, my thought is that it was not from the pentobarbitone since no drug was detected in the stomach contents. This is partly why I think he took it to help him go through with the suicide, since it wasn't detected in his stomach, he likely took it at least 30 minutes before he died, so what remained had time to move into his small intestine. It is a fast acting drug, but when you take it orally it will act much slower then when injected, so it is possible it cleared from his stomach before he died. It is likely to have contributed to his death.
Yes pentobarbitone was not given as a therapy when the police found him. The mention of the blood level being similar to that used during intubation
was just reported to give some relevance to the blood level; that it was as high as that used therapeutically, not toxic, but did likely have some sedative effect on him.
Yes it would be nice if it had described what the police actually found, like 12 yellow capsules, or an empty bottle, or something more then just pentobarbitone was found. It does seem funny that the police took a blood sample. I would think only the coroner/medical examiner would take blood. I can't imagine that the police are trained well enough to know how and were to get the blood from. The femoral artery is the preferred location to get postmortem blood, other sites can give misleading results.
Yes I still think asthma could have contributed, though by how much I don't know. There was congestion of the respiratory tract without inflammation which may suggest he was exposed to irritating amounts of hydrogen sulfide, which may have triggered an asthma attack. Plus mucus was found in his lungs which could have been caused by asthma, though not a severe amount.
It does not seem like any one thing by itself would have been able to kill him, but all of these factors together was very likely to be the cause. The new report only supports what I had thought before in my letter of opinion. There are still some details that are not clear, but it seems very convincing that your son had died from both hydrogen sulfide and pentobarbitone, which possibly aggravated asthma, further contributing to respiratory failure.
I hope this answers your questions. If you still have a question, just let me know.