My take, for what it is worth!
“Michael was frantic to get Fredo on that plane out of Cuba†because Fredo was still Michael's brother and wanted Fredo safely out of Havana “looking out for his brother's welfareâ€
Yeah, right...Michael had just learned that Fredo had betrayed him, nearly resulting in his and Kay's being killed...and he's looking out for his brother's welfare.
No wonder the Pope gave him a Knighthood.