The Strong move quiet the weak start riots. I believe during the movie when Michael said that Clemenza and Tessio couldn't break off from the family Clemenza seemed mad and Tessio was a little mad at first and then kinda just let it go. Tessio probably wouldn't have let it go and shaked Michael's hand after unless he had a trick up his sleeve. Tessio moved like a snake and because everyone thought he was in the background, that made his job a little easier.

"Well you just do what I tell you to do! Goddamn it! If I had a wartime consiglieri -- a
Sicilian -- I wouldn't be in this shape! Pop had Genco -- look what I got." - Sonny Corleone