I literally warned him about this in general chat, multiple times. Sent him medical/lay documents about B12 deficiency and how N2O is metabolized using B12. I also remember how he tried N2O and his first reaction was "this is it?" and thought it sucked. But I think he was also a few bottles of DXM deep.
Tetra is the exact kind of person who forces lawmakers to protect people from themselves by banning certain substances. Except those kinds of people will just move onto something else and kill themselves a different way while everyone else has to deal with new guard rails like giving their ID for cold medicine.