Achro flipped Mafia
From your argument, this makes sense why Mafia wouldn’t kill Achro, however this does not make sense for why Serial Killer wouldn’t kill Achro n1.
Serial Killer had no knowledge that Achro was mafia, so thusly obviously didn’t chose to not attack Achro because of that fact.
If it’s commonplace for Achro to die N1, then why wouldn’t the serial killer attack him?
That is… UNLESS THE SERIAL KILLER INTENTIONALLY CHOSE TO SPARE ACHRO TO LATER PUSH HIM UNDER THIS PREMISE