im not a security expert so dont trust me , but this happened in the past multiple times with same file , cleary the fact that blizzard made this happen again is very very bad.
Last time it happened i checked daily the virustotal report of the file , first days only some av was reporting it , successive days multiple av reported it , after a week multiple av started to remove it from positive list ( like it was a false positive ).
What i suspect is instead of preventing the problem , blizzard sends the file to big av vendors to check it and whitelist it , but this don’t prevent early heuristic detection’s.
edit: at least back in the past , they put it in the know issues
THIS IS FROM AN OLD PATCH , NOT CURRENT PATCH