I clicked on the manga link and found this:

Description
From Wikia:

Dragon Ball: Episode of Bardock is a three chapter manga created by Ooishi Naho and based on the video game Dragon Ball Heroes. It features a spin-off scenario taking place after the events of the TV special Dragon Ball Z: Bardock - The Father of Goku, in which Bardock survives after his confrontation against Frieza and turns into a Super Saiyan.
This should make clear that it's not canon, just a spinoff, like SS3 Trunks.