Sorry I was not clear about my sources
Extracts:
Remember,Solozzo was not a made guy
Vito's slipup Tom also found out about Tattaglia connection which Sollozzo hadn't revealed, as evident from Sollozzo's “my complimentsâ€
It seemed Sollozzo hadn't revealed the Tattaglia connection ie: Sollozzo still gotten to see Vito without using a major family vouching for him as leverage
Vito saw Sollozzo because as Vito said "Vito heard that Sollozzo is a serious man, to be treated with respect"
Tattaglia vouched for Solozzo, as Vito said to Sol before he said "no."
So how do we figure that “Tattaglia vouched for Solozzoâ€