2 teaspoons by most measurements of a teaspoon is not even close to the recommended 20 gms of SN in water. I see no mention of it being put into water, perhaps he just gulped down two spoonfuls of SN and hoped for the best. Yes, it is possible to die with less, but you are leaving it more up to chance as this guy found out.
Additionally, it notes that he has irritable bowel syndrome, and as far as I know there have been concerns about the effectiveness of SN with people who have digestive issues like that. One should take their own health issues into account and how it could complicate a method.
There is no reason to be alarmed based on the case of one person who seems to not have followed the recommended regime at all.
There was a former child actor, Matthew Mindler, who committed suicide with SN. It was discussed a bit on SS. And was probably another thing that made a lot of the existing ways to obtain SN disappear.