Yup. My understanding is that it was a propaganda spread by the right wing in order to discredit Kim Il Sung at that time. It's largely accepted as a conspiracy by the contemporary history communities IIUC.
Do you happen to have any historical evidence or perspective which supports the theory that right wing people pushed this the false history - or that the right wing conspiracy is widely accepted by the contemporary historical communities? I'd like to read.
Also note that the original article explicitly says "THIS IS UNEVALUATED INFORMATION".