And Joe probably DID warn him but that wouldn't change a thing. Galante knew he had a target on his back, he had the zip faction protecting him along with his two trusted bodyguards. He was always careful and only went to trusted joints, etc with trusted people. Joe and Mary's restaurant was owned by a cousin of his if I'm not mistaken.

Galante believed they couldn't get to him since he had an army of killers, or maybe he just didn't believe the other families would really set their differences aside, get together and take him out by any means. Regardless, Joe Bonanno's warning wuldn't/couldn't make any real difference to the outcome.