I don't think either is the type of guy to duck a fight. I reckon it's promoter politics unfortunately.
Said this months ago: no one cares about this fight outside of hardcore fans and those with ethnic/religious ties to either Bivol or Betetbiev It's sad but people want Bivol-Canelo 2 @ 168 and Beterbiev-Smiff
There isn't the money for the fight to happen right now. Expect Saudi to make a deal soon especially with Beterbiev being Muslim. Beterbiev has a mandatory in Callum Smith so Bivol will rematch Canelo in September. Not ducking. I expect the fight to happen in 2024 though as Beterbiev will likely face another mandatory in Stepien at the end of the year.