It’s a way more winnable fight for Jones than Ngannou. Jones has never fought anyone nearly as big and strong as Francis, in his last few he was getting tuned up on the feet by 185ers and is coming in rusty after 3 years off. Ngannou would’ve walked in 280lbs, the much bigger guy, and there’s no guarantee Jon can get him down before getting decapitated or rocked by a glancing shot.
Gane isn’t a power puncher, and is a worse grappler than Francis, and smaller. Jones has way more opportunity and less risk in this fight.