people here are touching on something i was thinking yesterday. something has to have gone wrong here, as we have over 6 years of experience with SN on the forum (plus the testimony of Exit International), and none of them have gone this wrong. sure, some people have had similar experiences of being afraid, regretting the decision due to SI, enduring more suffering than expected. but talking mostly coherently for over an hour is suspicious. most people pass out in under 40 minutes (usually under 20 minutes though), and toward the end they are quite incapable of doing much.
so i suspect they either used nitrate, in which case they are definitely still alive. or if it was nitrite, despite them claiming they "followed the rules" they didn't drink their second glass till after an hour had passed. as soon as they did, they seemingly passed out in under 20 minutes (last msg was 16 minutes after the second glass was downed). we also don't know if they used Meto, which is important for speeding up gastric emptying so more SN can enter your small intestine quicker. they may have vomited too much too soon, and then since they waited an hour to drink their second glass they suffered.
so people here having doubts about SN is more than okay, use whatever methods you feel are right for you. but it's important to note that this is absolutely outside of the norm, and all suicide methods can go wrong. but i'd still say SN is one of the better methods simply due to it not causing very much permanent damage if you fail. and the suffering isn't as bad as other poisons. but as with all methods, you have to do it right and by the book.