From this
article (Page 2, Discussion, 2nd paragraph): "Nitrite is also a potent vasodilator and can
cause coronary ischemia and stroke as a result of hypotension, tachycardia, and hypoxia."
Also
article about survived case with brain damage: "Delayed post-hypoxic leukoencephalopathy (DPHL) is a demyelinating syndrome that occurs days to weeks after the brain has recovered from a coma. It is caused by the period of hypoxia and is characterized by mental disorders, extrapyramidal system symptoms, and motor changes. Common causes include cardiogenic shock, severe anemia, massive blood loss, and poisoning. There are only a few reports of DPHL due to nitrite poisoning in literature.
Most patients usually recover completely. However, DPHL can easily induce long-term neurological deficits. Within a few weeks, patients with mild symptoms gradually begin to recover some functions, such as speaking and walking. After 1ββ2 years, most patients return to their baseline level, but following such poisoning, cognitive impairment including short-term memory deficits and fatigue may persist and hamper the patient's independence, reducing their quality of life."
People deserve to know about possible risks before choosing method, sharing true negative information is not fear mongering, especially provided with links to articles. While trying to hide all negative information about suicide method as you propose is unethical and inhuman. Especially trying to hide or deny cases when SN was painful or caused suffocation.
Regarding failed SN attempt, this is not the first time people survived SN without vomiting or vomited 3-5 hours later after SN and survived, 3-5 hours is a lot of time for SN because usually it takes 1-4 hours to kill you.
You can find several such cases in this
document (dartz, Johnrio, Suicidal4Ever). Plus this case.