Tessio & Clemenza were pros, they had been around the block.

They were already frustrated at the 'handcuffs' Michael had placed on them. They did not like the boss's kid, former civilian, calling the shots. They didn't trust that Michael knew what he was doing.

They knew walking into that office that they would be forbidden to recruit new men and they'd be asking to form their own families. What they probably did not count on was Vito backing Michael so completely.

This was not an impromptu request.

Apple