Warning! Spoilers ahead for Dragon Ball Super chapter 76!
In Dragon Ball Super, The Namekian Monaito just tried to convince his companion Granolah the Cerealian to stop fighting Goku, and by extension Vegeta, by revealing that Goku's father Bardock saved both of them from mass genocide.
Granolah has been obsessed with seeking vengeance on the Saiyan race ever since they slaughtered his people under the tyrannical banner of Frieza. When the Cerealian learned about Goku and Vegeta's existence, he deceived them into coming to Planet Cereal (like what happens in the original Broly movie) so he could enact his revenge, an act of retribution that both Saiyans have been unable to quell, but that Monaito may have succeeded in achieving.
Monaito didn't know about the ensuing battle until he just happened to stumble upon Granolah's rampage by accident at the very end of chapter 76. It's understandable why Granolah hid his plan to eradicate both Saiyans from Monaito. Monaito, who had created planet Cereal's own Dragon Balls, advised Granolah not to use them for vengeance, but it's obvious that the Cerealian went against the Namekian's better judgment when Granolah made his wish to become the strongest warrior in the universe. Monaito is a grandfather figure to Granolah and the Cerealian obviously didn't want to disappoint him but was too overcome by his anger for what happened to his people that he couldn't stop himself. He even accepted the penalty of losing most of his life in return for his wish. While it's currently unknown why Monaito failed to tell Granolah the truth about how they survived the Cerealian genocide until now, the Namekian obviously didn't want Granolah to murder their savior's son without knowing the truth.
Although Dragon Ball Super hasn't divulged the details as to why the Saiyan Bardock saved a Cerealian during Frieza's mission to destroy them, it humanizes his character. In the reboot seen in the Dragon Ball Super: Broly film adaptation, Bardock obviously loves his family enough to warn them of his suspicions of Frieza and to devise a plan to save their son who would later be known as Goku. But, more importantly, his treatment of other species is not shown, unlike his original portrayal in Bardock: The Father of Goku who was more ruthless and uncaring towards his enemies, hence why he was cursed by his defeated opponent to see the future. It's quite possible that Bardock was much more caring as Dragon Ball Super suggests, and Broly's ambiguity allows this.
Interestingly, it's obvious that Bardock could not have performed such a daring rescue during the events of Dragon Ball Super: Broly when he first becomes suspicious of Frieza's plan to eradicate his kind. He's first seen flying back home from battle to planet Vegeta and stays there the entire time. So it's not as though Bardock's decision to save them could have been fueled by his suspicions about Frieza in a last-ditch effort to undermine him. This was an act purely done out of the goodness of his heart. In fact, it's possible that the battle Bardock was returning home from at the beginning of the film was planet Cereal. Both events happened around the same time.
Regardless, the Namekian Monaito will likely reveal in the next chapter the whole truth behind what happened on that fateful day when Bardock rescued him and Granolah so many years ago. There's also a good chance it will confirm a fan theory that Goku and Vegeta will team up with Granolah and then possibly fight against Frieza. But more importantly, the fact that Dragon Ball Super: Broly left Bardock's character open to being more kindhearted to his enemies allowed for this unexpected twist to happen.