Cognitive dissonance is deeply uncomfortable and most people will double down on whatever will validate their priors rather than face a preponderance of sources that contradict them.
In this case they're biased for reality since there is a genocide happening in Gaza rn. But when the person saying this also dismisses a genocide as "not genocide, it's a war crime" and then unironically sites a source that's ran by Zionists, that's how you know you're not dealing with someone who is speaking in good faith on this issue