Sorry I was not clear about my sources

Extracts:
Originally Posted by Lou_Para
Remember,Solozzo was not a made guy

Vito's slipup
Originally Posted by Lana
Tom also found out about Tattaglia connection which Sollozzo hadn't revealed, as evident from Sollozzo's “my compliments”

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"

Originally Posted by Turnbull
Tattaglia vouched for Solozzo, as Vito said to Sol before he said "no."
So how do we figure that “Tattaglia vouched for Solozzo”