https://travel.state.gov/content/travel/en/legal/visa-law0/visa-bulletin/2024/visa-bulletin-for-may-2024.html
This is what you need to keep an eye on, he will be F2b and cross reference with your Country.
All I know is that in the hundreds of similar cases we have seen eventually it comes out why, sometimes it feels like pulling teeth.
They do not send them back to die without a reason.