I don't know if Sadkin had something to do with Goats Head Soup sessions.
This is my wild guess.
Paul Rodgers visited Jamaica with Chris Blackwell in 1972.
He recorded I Just Wanna See You Smile with The Maytals.
At some point during his stay, Paul made a courtesy visit to Terra Nova Hotel in Kingston where The Stones stayed at that time.
It is highly likely that Paul and The Stones introduced Sadkin to each other.
Seeing his involvement in the album "The Law". Sadlom developed a good relationship with Paul since then.